Recycled raw material composition and method for preparing same

Abstract

The present invention relates to a recycled raw material composition obtained through depolymerization of a waste polyester raw material, a method for preparing same, and a recycled polyester resin and a molded article which are manufactured using same. The recycled raw material composition comprises bis(2-hydroxyethyl) terephthalate (BHET) having a stabilized crystal form.

Description

Regenerated raw material composition and method for producing the same

[0001] The present invention relates to a recycled raw material composition comprising a recycled raw material obtained through a process of regenerating waste polyester raw material and having a stabilized crystal form, and a method for producing the recycled raw material composition.

[0002] Among the polymers closely used in modern life, polyester is widely used as a material for beverage or food containers, various packaging films, and various interior and exterior materials such as panels, shelves, and partitions due to its excellent mechanical strength, heat resistance, transparency, and gas barrier properties.

[0003] Due to the widespread use of these materials, waste from plastics such as polyester is generated annually at a rate that is difficult to manage, and countries around the world are recently establishing regulations and measures for recycling waste plastic resources, including waste polyester.

[0004] There are physical and chemical methods for recycling the waste polyester, but the physical recycling method is not widely applied because it cannot guarantee purity. On the other hand, the chemical recycling method depolymerizes the waste polyester by breaking the ester bonds, and uses reactions such as glycolysis, hydrolysis, methanolysis, and aminolysis. Among these, glycolysis decomposes the waste polyester by adding a glycol such as ethylene glycol or diethylene glycol, and a composition mainly containing bis(2-hydroxyethyl) terephthalate (BHET) is obtained. The bis(2-hydroxyethyl) terephthalate included in the composition can be used as a polymerization raw material for unsaturated polyester or ester polyol after purification.

[0005] However, the composition containing the above bis(2-hydroxyethyl) terephthalate (BHET) has a relatively high content of impurities, and thus there is a limit to obtaining high-purity and high-quality bis(2-hydroxyethyl) terephthalate (BHET) therefrom. Specifically, the composition contains by-products such as monohydroxyethyl terephthalate (MHET) and 2-hydroxyethyl[2-(2-hydroxyethoxy)ethyl] terephthalate (DEG-ester-1), which are generated by side reactions during the depolymerization process of waste polyester, and these act as impurities and lower the purity and quality of the composition containing BHET.

[0006] Meanwhile, BHET has hygroscopicity depending on its chemical structure, which affects the storage and transportation of compositions containing BHET, thereby reducing the handling properties of the compositions. Specifically, compositions containing BHET are typically in powder form, and due to the hygroscopicity of BHET, if moisture is absorbed during storage and transportation, the BHET powder may fuse and form lumps, which causes inconvenience to users handling the compositions. In addition, BHET that has absorbed moisture may also exhibit compositional changes, making it difficult to apply compositions containing BHET as polymerization raw materials.

[0007] In order to solve the above-described conventional problems, the inventors of the present invention have conducted various studies, and as a result, they have confirmed that by controlling the formulation of a renewable raw material composition containing bis(2-hydroxyethyl) terephthalate (BHET) and stabilizing the crystal form of BHET, the hygroscopicity of BHET is significantly reduced, and a renewable raw material composition having excellent handling properties (specifically, storage properties, transportability, ease of injection, etc.) and high purity and high quality is obtained.

[0008] Accordingly, the object of the present invention is to provide a regenerative raw material composition having a controlled formulation and containing BHET having a stabilized crystal form, and a method for producing the same.

[0009] In addition, another object of the present invention is to provide a recycled polyester resin and a molded product manufactured using the above-described recycled raw material composition.

[0010] In order to solve the above problem, the present invention provides a recycled raw material composition obtained through depolymerization of waste polyester raw material, A recycled raw material composition is provided, which comprises bis(2-hydroxyethyl)terephthalate (BHET) represented by , and when analyzed by X-ray diffraction (XRD), the BHET has a γ crystal form, an α crystal form, or a combination thereof.

[0011] In addition, the present invention comprises: (1) a step of depolymerizing a waste polyester raw material to obtain a product; (2) a step of purifying the product to obtain a liquid purified product; and (3) a step of solidifying the liquid purified product using a granulator. The present invention provides a method for producing a recycled raw material composition comprising bis(2-hydroxyethyl) terephthalate (BHET), which is represented by , and wherein, when analyzed by X-ray diffraction (XRD), the BHET has a γ crystal form, an α crystal form, or a combination thereof.

[0012] In addition, the present invention provides a recycled polyester resin manufactured from a polymerization raw material including the above-described recycled raw material composition and a molded article manufactured from the above-described recycled polyester resin.

[0013] The regenerative raw material composition according to the present invention is manufactured through a specific formulation process and has a granule formulation while including BHET having a stabilized crystal form (specifically, γ crystal form, α crystal form), so that the hygroscopicity (or moisture content) can be significantly lower than that of a conventional composition having a powder formulation while including BHET having any crystal form. Accordingly, the regenerative raw material composition can have excellent handling properties (specifically, storage properties, transportability, ease of injection, etc.) because the fusion caused by the hygroscopicity of BHET hardly occurs during storage and transportation.

[0014] In addition, since the regenerative raw material composition according to the present invention has a very low content of by-products (low molecular weight compounds that are impurities), it can exhibit high purity and high quality.

[0015] Therefore, when the recycled raw material composition according to the present invention is used as a polymerization raw material, it is possible to provide a recycled polyester resin having excellent quality (e.g., color characteristics) and a molded product using the same while ensuring that the manufacturing process of the recycled polyester resin is operated stably.

[0016] Figures 1 to 3 show the results of X-ray diffraction (XRD) analysis of the raw material compositions of Examples 1 and 3 and Comparative Examples 1 and 3 in Test Example 1.

[0017] Figure 4 is an image confirming whether fusion occurred in the raw material compositions of Example 1 and Comparative Example 1 in Test Example 4.

[0018] Figure 5 is a reference drawing for explaining the shape of granular particles made of the regenerative raw material composition of the present invention.

[0019] Hereinafter, the present invention will be described in detail. Herein, the present invention is not limited to the contents described below, and may be modified in various forms as long as the gist of the invention is not changed.

[0020] The word "comprising" or "including" in this specification is intended to specify particular features, regions, steps, processes, elements and / or components, and does not exclude the presence or addition of other features, regions, steps, processes, elements and / or components, unless specifically stated to the contrary.

[0021] In this specification, the terms first, second, etc. are used for the purpose of distinguishing one component from another, and the components are not limited by the terms.

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

[0023]

[0024] Conventional recycled raw material compositions obtained through chemical recycling of waste polyester mostly contain BHET and are in powder form. At this time, the BHET has hydroxyl groups, known as representative hydrophilic groups, at both ends, exhibiting the characteristic of readily absorbing moisture. Thus, the BHET contained in conventional recycled raw material compositions exhibits the aforementioned characteristics, but is in a powder form with a large specific surface area and various crystal forms, resulting in highly hygroscopic and unstable crystallinity. This causes BHET to fuse and change its composition, resulting in process difficulties in the use of compositions containing BHET.

[0025] Accordingly, the present invention aims to provide a recycled raw material composition comprising BHET having a stabilized crystal form with remarkably low hygroscopicity by manufacturing the recycled raw material composition through a specific formulation process, and this will be described in detail as follows.

[0026]

[0027] Regenerated raw material composition

[0028] The recycled raw material composition of the present invention is obtained through depolymerization of waste polyester raw material, A composition comprising bis(2-hydroxyethyl)terephthalate (BHET), wherein when analyzed by X-ray diffraction (XRD), the BHET has a γ crystal form, an α crystal form, or a combination thereof.

[0029] The above-mentioned waste polyester raw material can be obtained from polyester products discarded after use. Specifically, the waste polyester raw material can be obtained by preprocessing various waste polyester (e.g., polyethylene terephthalate (PET)) products, such as beverage bottles, fabrics, films, cases, boxes, partitions, shelves, protective panels, packaging, building materials, and interior and exterior materials, which are waste products discarded by users after use.

[0030] The above pretreatment may comprise a process of removing other plastics (different components), metals, and other foreign substances mixed in the waste, washing the waste, and then crushing it using a crusher. After undergoing this pretreatment process, the waste polyester raw material may take the form of flakes, scrap, or powder. Furthermore, the waste polyester raw material may have a fine structure, such as fibers.

[0031] The bis(2-hydroxyethyl)terephthalate (BHET) included in the recycled raw material composition of the present invention is the recycled raw material targeted in the present invention, and may be included in the recycled raw material composition at a high content. Specifically, when the recycled raw material composition is analyzed by high performance liquid chromatography (HPLC), the peak area ratio of the bis(2-hydroxyethyl)terephthalate (BHET) may be 80% or more. More specifically, the peak area ratio of the BHET may be 85% or more, 88% or more, 90% or more, 92% or more, 94% or more, 96% or more, or 98% or more (e.g., 90 to 99.9%, 95 to 99.5%, or 97 to 99%), and thus, the recycled raw material composition may exhibit high purity and high quality (e.g., excellent color characteristics).

[0032] The peak area ratio (%) of BHET can be confirmed by measuring the ratio of the peak area of ​​BHET to the total peak area in the spectrum of the recycled raw material composition obtained through HPLC analysis.

[0033] According to the present invention, the BHET included in the regenerative raw material composition has a stabilized crystal form. Specifically, the BHET may have the most stable crystal form, the γ crystal form, the α crystal form, or a combination thereof. Since the BHET has the crystal form, it has a high apparent density and a low moisture content (hygroscopicity), thereby providing a regenerative raw material composition with excellent handling properties (storability, transportability, ease of injection, etc.).

[0034] According to the present invention, the γ crystal form and the α crystal form of the BHET can be distinguished by the X-ray diffraction (XRD) peak analysis results. For example, these crystal forms can be identified by the intensity and order (pattern) of the peak showing the strongest intensity (intensity) in the X-ray diffraction peak. Specifically, the γ crystal form of the BHET can be identified by the first largest (first highest intensity) X-ray diffraction peak (P γ1st ) appears in the 2θ range of 23.0° to 23.9°, and the second largest (second most intense) X-ray diffraction peak (P γ2nd ) appears in the 2θ range of 23.9° to 24.9°. The α crystal form of BHET has the first largest (first highest intensity) X-ray diffraction peak (P α1st ) appears in the 2θ range of 23.0° to 23.9°, and the second largest (second most intense) X-ray diffraction peak (P α2nd ) appears in the 2θ range of less than 16.1° to 17.0°.

[0035] These BHETs may not include the β crystal form or the δ crystal form. Specifically, the X-ray diffraction maximum peak (P) of the δ crystal form of BHET δmax ) appears in the 2θ range of 10° to 12°, and the maximum X-ray diffraction peak (P) of the β crystal form of BHET βmax ) appears in the 2θ range of 18° to 20°, but in the BHET of the present invention, the maximum X-ray diffraction peak may not appear in the 2θ range of 10° to 12° and / or the 2θ range of 18° to 20°.

[0036] According to the present invention, the BHET has the highest intensity (highest) X-ray diffraction peak (PI) in the 2θ range of 23.0° to less than 23.9° when analyzed by X-ray diffraction (XRD). max) may appear. This may mean that the main crystal form of the above BHET is the γ crystal form or the α crystal form.

[0037] In addition, the BHET may have an SC ratio of 1.0 or more according to the following Equation 2 when analyzed by the X-ray diffraction (XRD). Specifically, the SC ratio may be 2 or more, 5 or more, 7 or more, 10 or more, 13 or more, 15 or more, 17 or more, 20 or more, 23 or more, or 25 or more (e.g., 1 to 28, 4 to 27.5, 9 to 27, 12 to 26.5, or 18 to 26). The SC ratio refers to the ratio (distribution ratio) of the β crystal form to the α and γ crystal forms, and a larger SC ratio may mean that the BHET has the α and γ crystal forms as its main crystal forms.

[0038] [Formula 2]

[0039] SC ratio = PI max1 / PI max2

[0040] In the above equation 2,

[0041] PI max1 is the intensity of the largest X-ray diffraction peak appearing in the 2θ range of less than 23.0° to 23.9° (the range where it is judged to have α and γ crystal forms),

[0042] PI max2 is the intensity of the largest X-ray diffraction peak appearing in the 2θ range of 18.0° to 20.0° (the range in which it is judged to have a β crystal form).

[0043] According to the present invention, the regenerative raw material composition may be a solid regenerative raw material composition, and thus the bulk density may be measured. Specifically, the regenerative raw material composition may have an apparent density of 0.2 to 0.8 g / ml, and more specifically, 0.3 to 0.8 g / ml, 0.4 to 0.8 g / ml, 0.5 to 0.78 g / ml, 0.55 to 0.77 g / ml, 0.6 to 0.76 g / ml, or 0.64 to 0.75 g / ml. When the apparent density is within the above range, the specific surface area of ​​the regenerative raw material composition is relatively small, and thus a regenerative raw material composition having a significantly low moisture content may be provided.

[0044] Specifically, the regenerative raw material composition may have a moisture content change rate over time of less than 0.3 according to the following Equation 1. More specifically, the moisture content change rate over time may be 0.25 or less, 0.2 or less, 0.1 or less, 0.09 or less, 0.08 or less, 0.06 or less, 0.05 or less, 0.04 or less, or 0.03 or less (e.g., greater than 0 to 0.29, greater than 0 to 0.15, 0.01 to 0.07, or 0.01 to 0.05).

[0045] [Formula 1]

[0046] The rate of change in the function rate over time = (M7- M0) / 7

[0047] In the above equation 1,

[0048] M7 is the unit-excluding value of the saturation moisture content measured by the Karl Fischer method after storing the above-mentioned raw material composition at room temperature for 7 days.

[0049] M0 is a numerical value excluding the unit from the initial moisture content measured by the Karl Fischer method for the above-mentioned raw material composition.

[0050] In addition, the above-mentioned raw material composition may have a saturation moisture content of less than 1.0% as measured by the Karl Fischer method after storage at room temperature for 7 days. Specifically, the saturation moisture content may be 0.9% or less, 0.7% or less, 0.6% or less, 0.5% or less, 0.4% or less, or 0.3% or less (e.g., greater than 0 to 0.99%, greater than 0 to 0.8%, 0.01 to 0.6%, or 0.01 to 0.5%).

[0051] The above moisture content change rate over time and the saturation moisture content indicate the degree of hygroscopicity of BHET, and the fact that these ranges appear as described above may mean that the hygroscopicity of BHET included in the recycled raw material composition is very low. In other words, the recycled raw material composition has a significantly low moisture content, and as a result, fusion of the recycled raw material composition due to moisture absorption can be prevented during storage and transportation.

[0052] Meanwhile, the Karl Fischer method is a moisture measurement method that quantifies the moisture content of a sample through titration. Specifically, the Karl Fischer method can be a method of quantifying the moisture content of a sample using a Karl Fischer reagent by utilizing the quantitative reaction of water (H2O) with iodine (iodine, I2) and sulfur dioxide (sulfur dioxide, SO2) in the presence of an organic base such as pyridine (C5H5N) and a lower alcohol such as methanol (CH3OH), as shown in the reaction equation below.

[0053] [Reaction formula]

[0054]

[0055] According to the present invention, the regenerative raw material composition may be a solid regenerative raw material composition and may have a granular formulation. The granular formulation may have a larger particle size than a powder formulation, for example, a particle size of 0.1 to 20 mm, 0.5 to 15 mm, or 1 to 10 mm. The particle size may refer to the longest length of the particle. Since the regenerative raw material composition has a granular formulation, it may exhibit a low moisture content and excellent handleability.

[0056] Meanwhile, the shape of the granules may or may not be constant, and may be, for example, circular or oval. Specifically, the granules may be oval in which the distance from the center of the longitudinal or transverse section to the outer surface varies depending on the direction (or angle) (see Fig. 5).

[0057] According to the present invention, when the regenerative raw material composition is analyzed by high-performance liquid chromatography (HPLC), the peak area ratio of the low molecular weight compound represented by the following chemical formula 1 may be 20% or less:

[0058] [Chemical Formula 1]

[0059]

[0060] In the above chemical formula 1,

[0061] R 1 and R 2 are each independently selected from the group consisting of hydrogen, alkyl, hydroxyalkyl, alkyl acetate, alkoxyalkyl and aryl, provided that in the low molecular weight compound represented by the above chemical formula 1, Bis(2-hydroxyethyl)terephthalate (BHET), which is indicated as , is excluded.

[0062] The above R 1 and R 2In the definition, alkyl is a straight or branched chain C1 to C6 alkyl, hydroxyalkyl is a C1 to C6 hydroxyalkyl, alkylacetate is a C1 to C6 alkylacetate, alkoxyalkyl is a C1 to C6 alkoxyalkyl, and aryl is a C6 to C 14 It may be an aryl.

[0063] Specifically, the low molecular weight compound represented by the above chemical formula 1 is monohydroxyethyl terephthalate (MHET), bis(2-hydroxyethyl)isophthalate (BHEI), terephthalic acid (TPA), 2-hydroxyethylmethyl terephthalate (HEMT), bis(2-hydroxyhexyl) terephthalate (BHHT), bis(2-hydroxybutyl) terephthalate (BHBT), 2-hydroxyethyl(2-acetoxyethyl) terephthalate (HA-ester-1), bis(2-acetoxyethyl) terephthalate (HA-ester-2), 2-hydroxyethyl[2-(2-hydroxyethoxy)ethyl] terephthalate (DEG-ester-1), It may include at least one selected from the group consisting of bis[2-(2-hydroxyethoxy)ethyl]benzene-1,4-dicarboxylate (DEG-ester-2) and bis{2-[2-(2-hydroxyethoxy)ethoxy]ethyl}terephthalate (TEG-ester-2).

[0064] The low molecular weight compound represented by the above chemical formula 1 refers to a by-product (impurity) generated by a side reaction during the depolymerization process of waste polyester raw materials. When the recycled raw material composition of the present invention is analyzed by HPLC, its peak area ratio may be 20% or less, so that it may have high purity and very low change in yellowness over time. Specifically, when the recycled raw material composition is analyzed by HPLC, the peak area ratio of the low molecular weight compound represented by the above chemical formula 1 may be 15% or less, 13% or less, 10% or less, 5% or less, 3% or less, 1% or less, 0.9% or less, 0.7% or less, or 0.5% or less (e.g., more than 0 to 10%, 0.01 to 7%, or 0.1 to 2.5%).

[0065] The peak area ratio (%) of these low molecular weight compounds can be confirmed by measuring the ratio of the peak area of ​​the low molecular weight compounds to the total peak area in the spectrum of the recycled raw material composition obtained through HPLC analysis.

[0066] The molecular weight (average molecular weight) of the low molecular weight compound represented by the above chemical formula 1 may be 165 to 460 g / mol, and specifically, 170 to 450 g / mol, 200 to 400 g / mol, or 210 to 345 g / mol.

[0067] The regenerative raw material composition of the present invention, which includes BHET having a stabilized γ crystal form and / or α crystal form, has a granular formulation and a remarkably low moisture content, thereby exhibiting excellent handleability, and the content of low molecular weight compounds is controlled, thereby exhibiting high purity and high quality. Therefore, the regenerative raw material composition of the present invention can be usefully used as a polymerization raw material for various polymers (e.g., polyester or ester polyol).

[0068]

[0069] Method for producing a regenerative raw material composition

[0070] The method for producing a recycled raw material composition of the present invention comprises the steps of (1) depolymerizing a waste polyester raw material to obtain a product; (2) purifying the product to obtain a liquid purified product; and (3) solidifying the liquid purified product using a granulator, which are specifically described as follows.

[0071] Here, the regenerative raw material composition manufactured through the above steps (1) to (3) is A compound comprising bis(2-hydroxyethyl) terephthalate (BHET) represented by , wherein when analyzed by X-ray diffraction (XRD), the BHET has a γ crystal form, an α crystal form, or a combination thereof, and a detailed description thereof is omitted as it is the same as described above.

[0072]

[0073] Step (1): Depolymerization

[0074] According to the present invention, step (1) is a step of obtaining a product by depolymerizing waste polyester raw materials through physical or chemical methods. Specifically, the depolymerization may be performed through a chemical method utilizing reactions such as glycolysis, hydrolysis, methanolysis, or aminolysis.

[0075] For example, the depolymerization may be achieved through a glycolysis reaction in which the polymer chains of the waste polyester raw material are decomposed by a glycol compound. The glycol compound is not particularly limited, but may be ethylene glycol, propylene glycol, diethylene glycol, or a combination thereof.

[0076] The amount of input (usage) of such glycol compounds is not particularly limited, but may be specifically 1.5 times or more, 2 times or more, 4 times or more, or 5 times or more, and 7 times or less, 6 times or less, 5 times or less, or 4.5 times or less (e.g., 1.5 to 7 times, 2 to 5 times, or 3 to 4 times) relative to the weight of the waste polyester raw material.

[0077] The temperature at which the above depolymerization is performed is not particularly limited, but may be 180 to 220°C, specifically 180 to 210°C, 185 to 200°C, 185 to 195°C, or 190 to 195°C. In addition, the time at which the depolymerization is performed is not particularly limited, but may be 1 to 30 hours from the time at which the temperature required for depolymerization is reached, specifically 1.5 to 15 hours, 2 to 10 hours, 2 to 8 hours, 2.5 to 6 hours, or 3 to 5 hours. As the depolymerization is performed at the above temperature and time, the glycolysis reaction can be performed smoothly, while minimizing the production of by-products.

[0078] This depolymerization can be carried out in the presence of a catalyst that activates the glycolysis reaction. The catalyst is not particularly limited as long as it is a commonly known catalyst, but may specifically include a metal acetate, an anhydride thereof, or a hydrate thereof. More specifically, the catalyst may be one or more compounds selected from the group consisting of zinc acetate, sodium acetate, cobalt acetate, and manganese acetate, a hydrate thereof, or anhydride thereof.

[0079] The amount of the catalyst to be added (used) is not particularly limited, but may be 0.001 to 3 parts by weight, 0.005 to 2 parts by weight, 0.01 to 1 part by weight, or 0.03 to 0.5 parts by weight relative to 100 parts by weight of the waste polyester raw material.

[0080]

[0081] Step (2): Purification

[0082] According to the present invention, step (2) is a step of purifying the product obtained through step (1) to obtain a liquid purified product. This step (2) may include a crystallization process for crystallizing the product.

[0083] Specifically, step (2) may include (2-1) a step of first purifying the product to obtain a first purified product; (2-2) a step of crystallizing the first purified product to obtain a crystal product; and (2-3) a step of second purifying the crystal product to obtain a second purified product. If the second purified product obtained through step (2-3) is in a liquid state, this may correspond to the liquid purified product obtained through step (2). Meanwhile, if the second purified product obtained through step (2-3) is in a solid state rather than a liquid state, step (2) may further include a step of (2-4) melting (or dissolving) the second purified product, and the obtained product may correspond to the liquid purified product obtained through step (2).

[0084] The primary purification of the above step (2-1) can be performed through a conventionally known process. Specifically, the primary purification can be performed by undergoing one or more of the following processes: filtration, ion exchange, distillation, and adsorption. Through this primary purification, unreacted glycol compounds and / or residual byproducts can be removed (separated), thereby further increasing the purity of the recycled raw material composition.

[0085] The above filtration process may include membrane filtration, filterate filtration, reduced pressure flash (cooling), solid-liquid separation, centrifugation, etc. By performing such filtration processes, fine particles and / or insoluble solid impurities contained in the obtained product can be removed.

[0086] The above ion exchange is a process that is typically performed using a known ion exchange resin. Specifically, the ion exchange resin may include a cation exchange resin, an anion exchange resin, an amphoteric ion exchange resin, a chelating resin, etc. The cation exchange resin may specifically be a strongly acidic cation exchange resin having a sulfonic acid group (-SO3H), or a weakly acidic cation exchange resin having a carboxyl group (-COOH). The anion exchange resin may be a strongly basic anion exchange resin in the form of a quaternary ammonium salt, or a weakly basic anion exchange resin having an amino group. By performing this ion exchange process, catalysts and / or metal foreign substances, etc. can be removed.

[0087] The above distillation may include processes such as vacuum distillation, thin film evaporation, falling film evaporation, and short path evaporation. By going through these distillation processes, unreacted glycol compounds, etc. can be removed.

[0088] The above adsorption is a process typically performed using a known adsorbent (e.g., activated carbon). By performing this adsorption process, a crystallized product (e.g., a recycled raw material composition containing bis-2-hydroxyethyl terephthalate (BHET)) can be obtained while removing other impurities.

[0089] The crystallization of the above step (2-2) is a step for crystallizing the primary purified product to have uniform crystallinity. The crystallization of the primary purified product is not particularly limited, but may be performed using an evaporation-type crystallizer or a jacket-type crystallizer. As the crystallization is performed using the crystallizer, low-molecular-weight impurities are efficiently removed, thereby obtaining a crystal product having uniform crystallinity.

[0090] The above-mentioned evaporative type crystallizer (vacuum depressurization crystallizer) evaporates the solvent contained in the primary purified material by lowering the pressure (decompression) in a vacuum state, thereby crystallizing the solid contained in the primary purified material, and may have a commonly known structure. When crystallization is performed through the above-mentioned evaporative type crystallizer, a uniform temperature change occurs throughout the primary purified material (crystallization occurs while maintaining a uniform temperature throughout), thereby preventing local crystallization or non-uniform crystallization from occurring. This evaporative type crystallizer can increase the effect by optimally controlling the temperature / pressure, etc. or performing the process in stages.

[0091] The jacket-type crystallizer directly cools the primary purified material using a cooling medium to crystallize the solid contained in the primary purified material, and may have a commonly known structure. The jacket-type crystallizer may have a stirring speed of 10 to 300 rpm, 30 to 250 rpm, 50 to 230 rpm, 70 to 200 rpm, 80 to 150 rpm, or 90 to 120 rpm. When the stirring speed is within the above range, uniform crystallization can be achieved while efficiently removing low-molecular-weight compounds. Meanwhile, the cooling medium is not particularly limited as long as it is commonly known, and specifically, water, an organic solvent (e.g., ethylene glycol), or a mixture thereof may be used.

[0092] The above crystallization may be performed at a cooling rate of 0.1 to 2.0 °C / min, considering the crystallinity of the obtained crystal product. Specifically, the cooling rate may be 0.1 to 1.5 °C / min, 0.1 to 1.0 °C / min, or 0.1 to 0.7 °C / min. For example, the crystallization of the first purified product may be performed by lowering the temperature of the first purified product to room temperature at the above cooling rate.

[0093] The secondary purification in step (2-3) above can be performed through a commonly known process. Specifically, the secondary purification can be performed by one or more of filtration, ion exchange, distillation, and adsorption. The description of this secondary purification is identical to that of the primary purification, and therefore, a detailed description will be omitted.

[0094] The melting (or dissolution) of the above step (2-4) can be performed by melting the secondary purified product through a commonly known process.

[0095]

[0096] (3): High-quality

[0097] According to the present invention, step (3) is a step of solidifying the liquid purified material obtained through step (2) using a granulator to obtain a regenerative raw material composition having a granular formulation. The granulator manufactures granular particles through a solidification process of quenching the liquid purified material, and a commonly known granulator can be used. Through the solidification in step (3), BHET granules (grains) having a relatively lower specific surface area than BHET powder are manufactured, and since the regenerative raw material composition includes such BHET granules, the moisture content is significantly low, and thus, the handling property is excellent, allowing the user to use it conveniently.

[0098] The temperature at which the above liquid purified product is solidified is not particularly limited, but considering the solidification efficiency, the size and shape control of the granule particles, etc., it may be 10 to 100°C, and specifically, it may be 10 to 95°C, 10 to 70°C, 10 to 60°C, 10 to 50°C, 20 to 90°C, 30 to 85°C, 40 to 80°C, or 50 to 80°C.

[0099]

[0100] Regenerated polyester resin

[0101] The recycled polyester resin of the present invention is manufactured from a polymerization raw material comprising a recycled raw material composition. Specifically, the polymerization raw material may comprise a recycled raw material composition; a diol component; and a dicarboxylic acid component.

[0102] The above-mentioned regenerative raw material composition contains bis(2-hydroxyethyl) terephthalate (BHET), and the description thereof is omitted as it is the same as described above.

[0103] The above diol component may specifically include at least one (e.g., at least two, at least three, or at least four) selected from the group consisting of ethylene glycol, recycled ethylene glycol, diethylene glycol, recycled diethylene glycol, 1,4-cyclohexanedimethanol, recycled 1,4-cyclohexanedimethanol, isosorbide, recycled isosorbide, neopentyl glycol, recycled neopentyl glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-propanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 2-methyl-1,3-propanediol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and derivatives thereof.

[0104] The above dicarboxylic acid component may specifically include at least one selected from the group consisting of terephthalic acid, recycled terephthalic acid, isophthalic acid, recycled isophthalic acid, dimethyl phthalate, recycled dimethyl phthalate, dimethyl terephthalate, recycled dimethyl terephthalate, 1,4-cyclohexane dicarboxylic acid, 1,3-cyclohexane dicarboxylic acid, dimethyl 1,4-cyclohexane dicarboxylate, dimethyl 1,3-cyclohexane dicarboxylate, 2,6-naphthalenedicarboxylic acid, diphenyl dicarboxylic acid, 4,4'-stilbene dicarboxylic acid, 2,5-furandicarboxylic acid, and 2,5-thiophenedicarboxylic acid.

[0105] The above-mentioned regenerated polyester resin can be manufactured by subjecting the above-mentioned polymerization raw material to an esterification reaction or an ester exchange reaction and then to a polycondensation reaction. The esterification reaction, the ester exchange reaction, and the polycondensation reaction can each be carried out under commonly known reaction conditions.

[0106] Meanwhile, in the production of the above-mentioned recycled polyester resin, one or more additives selected from the group consisting of commonly known catalysts, oxidation stabilizers, branching agents, coloring agents, crystallizers, and ultraviolet absorbers may be further used together with the above-mentioned polymerization raw materials.

[0107] These recycled polyester resins may be in the form of chips, pellets, or powder.

[0108] The regenerated polyester resin of the present invention is manufactured using a polymerization raw material including the above-described regenerated raw material composition, and thus exhibits high quality (e.g., excellent color characteristics), and can be efficiently utilized in various fields.

[0109]

[0110] molded products

[0111] The molded article of the present invention is manufactured from a recycled polyester resin. Specifically, the molded article is manufactured through molding the aforementioned recycled polyester resin and can have a variety of shapes and uses. Because it is manufactured from the aforementioned recycled polyester resin, the molded article can exhibit excellent transparency, along with heat resistance and mechanical strength.

[0112] The method for molding the regenerated polyester resin to manufacture the molded product is not particularly limited as long as it is a commonly known method, and specific examples thereof include injection molding, extrusion molding, pressure molding, vacuum molding, and blow molding.

[0113] These molded articles may be containers, films, sheets, fibers (woven, knitted, nonwoven, etc.), or interior or exterior materials.

[0114] The present invention is described in more detail through the following examples. However, the following examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention.

[0115]

[0116] [Example 1]

[0117] 1000 g of waste polyester scrap, 4000 g of ethylene glycol, and 0.35 g of zinc acetate anhydride were all placed together in a stainless steel (SUS) reactor. Then, the internal temperature of the reactor was increased to 195°C, and depolymerization was performed for 4 hours to obtain a product.

[0118] Insoluble solid impurities remaining in the obtained product (unreacted polymers (e.g., polyolefin, PVC, etc.) and other insoluble solids) were removed through a mesh filter, and the mixture from which the insoluble solid impurities were removed was transferred to a 10 L distillation device, and then distillation under reduced pressure at 130°C was performed to remove and recover unreacted ethylene glycol.

[0119] The obtained product from which unreacted ethylene glycol was removed was subjected to thin-film distillation at 220°C and 0.08 Torr in a thin-film distiller (VKL70-4S from VTA) to obtain crude BHET from which oligomers higher than dimers were removed.

[0120] Afterwards, for adsorption-crystallization, the above-mentioned BHET and distilled water were added to a 20 L adsorption tank, dissolved at a temperature of 70°C, 2.6 g of activated carbon was added, stirred at a temperature of 85°C for 30 minutes, and then filtered.

[0121] After the filtered solution was transferred to an evaporation type crystallizer, the evaporation conditions were adjusted to maintain a uniform temperature throughout (by adjusting the pressure from the low vacuum to the high vacuum region to induce an endothermic reaction due to water evaporation), and the solution was cooled to room temperature to proceed with crystallization.

[0122] The BHET crystals formed through crystallization and the mother liquor were separated into solid and liquid through pressure filtration, and the obtained BHET crystals were remelted to obtain a liquid purified product.

[0123] The obtained liquid purified product was solidified by quenching it at a temperature of 10 to 60°C through a granulator, thereby obtaining 1015 g of a BHET-containing composition in granular form.

[0124]

[0125] [Example 2]

[0126] 1000 g of waste polyester scrap, 4000 g of ethylene glycol, and 0.35 g of zinc acetate anhydride were all placed together in a stainless steel (SUS) reactor. Then, the internal temperature of the reactor was increased to 195°C, and depolymerization was performed for 4 hours to obtain a product.

[0127] Insoluble solid impurities remaining in the obtained product (unreacted polymers (e.g., polyolefin, PVC, etc.) and other insoluble solids) were removed through a centrifuge at 80°C, and the mixture from which insoluble solid impurities were removed was placed in a 20 L adsorption tank, 2.6 g of activated carbon was added, stirred at 85°C for 30 minutes, and then filtered.

[0128] After the filtered solution was transferred to an evaporation type crystallizer, the evaporation conditions were adjusted to maintain a uniform temperature throughout (the pressure was adjusted from a low vacuum to a high vacuum region to induce an endothermic reaction due to water evaporation) and the solution was cooled to room temperature to proceed with crystallization.

[0129] The product obtained through crystallization was transferred to a 10 L distillation device, and distillation under reduced pressure at 130°C was performed to remove and recover unreacted ethylene glycol. The BHET mixture from which unreacted ethylene glycol had been removed was subjected to thin-film distillation at 220°C and 0.08 Torr in a thin-film distiller (VKL70-4S from VTA) to obtain a liquid purified product (liquid BHET) from which dimers or higher oligomers had been removed.

[0130] The obtained liquid purified product (liquid BHET) was solidified by quenching it at a temperature of 10 to 60°C through a granulator, thereby obtaining 1070 g of a BHET-containing composition in granular form.

[0131]

[0132] [Example 3]

[0133] A crystallization process was performed using a jacket-type crystallizer in which direct cooling was performed using a cooling medium (cooling water) instead of an evaporation-type crystallizer, and quenching was performed at a temperature of 60 to 95°C, thereby obtaining 1005 g of a granular BHET-containing composition through the same process as Example 1.

[0134]

[0135] [Example 4]

[0136] 1000 g of waste polyester scrap, 4000 g of ethylene glycol, and 0.35 g of zinc acetate anhydride were all placed together in a stainless steel (SUS) reactor. Then, the internal temperature of the reactor was increased to 195°C, and depolymerization was performed for 4 hours to obtain a product.

[0137] The resulting product was added with 4,500 g of warm water and transferred to a 20 L adsorption tank. 2.6 g of activated carbon was then added to the transferred mixture, stirred at 85°C for 30 minutes, and filtered.

[0138] After the filtered solution was transferred to an evaporation type crystallizer, the evaporation conditions were adjusted to maintain a uniform temperature throughout (the pressure was adjusted from a low vacuum to a high vacuum region to induce an endothermic reaction due to water evaporation) and the solution was cooled to room temperature to proceed with crystallization.

[0139] The product obtained through crystallization was subjected to solid-liquid separation through pressure filtration, and the above-described adsorption process and crystallization process were performed once more.

[0140] The obtained product containing BHET crystals and mother liquor obtained through an additional process was subjected to solid-liquid separation through pressure filtration, and the obtained BHET crystals were remelted to obtain a liquid purified product.

[0141] The obtained liquid purified product was subjected to a solidification process of quenching at a temperature of 60 to 95°C through a granulator, thereby obtaining 951 g of a BHET-containing composition in granular form.

[0142]

[0143] [Comparative Example 1]

[0144] A crystallization process was performed through a jacket-type crystallizer in which direct cooling was performed using a cooling medium (cooling water) instead of an evaporation-type crystallizer, and a liquid purified product was dried with hot air at 60°C for 1 hour instead of a solidification process using a granulator, and 958 g of a BHET-containing composition in powder form was obtained through the same process as in Example 4.

[0145]

[0146] [Comparative Example 2]

[0147] 1121 g of a BHET-containing composition in powder form was obtained through the same process as Example 3, except that instead of performing the solidification process through a granulator, the liquid purified product was dried with hot air at 60°C for 1 hour.

[0148]

[0149] [Comparative Example 3]

[0150] A powder-form BHET-containing composition of 1094 g was obtained through the same process as Example 2, except that instead of performing the solidification process through a granulator, the liquid purified product was dried with hot air at 60°C for 1 hour.

[0151]

[0152] [Example 1]

[0153] The crystal form of BHET was confirmed by XRD analysis of the BHET-containing composition using Rigaku's Ultima(IV) model. The XRD pattern was measured in the 2Theta / theta 5-90 degree range, and the results are shown in Table 1 below.

[0154] Meanwhile, the XRD patterns (graphs) of Examples 1 and 3 and Comparative Examples 1 and 3 are shown in FIGS. 1 to 3.

[0155]

[0156] BHET crystal structurePI max1 2θ: 23.0°~23.9° less than PI max2 2θ: 18.0°~20.0°SC ratio α, β, γ, δExample 188740409521.7γ richExample 279992601413.3γ richExample 3115673449525.7α richExample 484815613313.8α richComparative example 122643612380.4β+α (β>δ)Comparative example 232755560700.6β+δ+α(β>α>δ)Comparative example 331060826100.4β+δ+α(β>δ>α)SC ratio (Stablized Crystal Ratio) = PI max1 / PI max2 PI max1 : Intensity of the largest X-ray diffraction peak appearing in the 2θ range of less than 23.0° to 23.9°PI max2: The intensity of the largest X-ray diffraction peak appearing in the 2θ range of 18.0° to 20.0°

[0157] Referring to Table 1 and FIGS. 1 to 3, it can be confirmed that the regenerated raw material compositions of Examples 1 to 4 according to the present invention include BHET rich in the γ crystal form or the α crystal form, whereas the regenerated raw material compositions of Comparative Examples 1 to 3 include BHET rich in the β crystal form and / or the δ crystal form.

[0158]

[0159] [Example 2]

[0160] About 0.01 g of a composition containing BHET was diluted in about 20 mL of methanol and analyzed by high-performance liquid chromatography (HPLC) (Model: Waters e2695; Column: C18 (4.6 x 250 mm), 5 μm; UV Detector: 242 nm; Injection volume: 10 μL; Eluent (Gradient) A: H2O+H3PO4, B: Acetonitrile). Afterwards, the peak area ratio (%) of the following components among the total peak area of ​​HPLC was confirmed, and the results are shown in Table 2 below.

[0161] - MHET: Monohydroxyethyl terephthalate

[0162] - BHET: bis(2-hydroxyethyl) terephthalate

[0163] - BHEI: Bis(2-hydroxyethyl)isophthalate

[0164] - DEG-ester-1: 2-hydroxyethyl[2-(2-hydroxyethoxy)ethyl]terephthalate

[0165] - DEG-ester-2: Bis[2-(2-hydroxyethoxy)ethyl]benzene-1,4-dicarboxylate

[0166] - ME-ester: 2-hydroxyethylmethyl terephthalate

[0167] - HA-ester: 2-hydroxyethyl (2-acetoxyethyl) terephthalate

[0168] - Dimer: BHET dimer

[0169] - Trimer: BHET trimer

[0170]

[0171] Total content (%) of low molecular weight compounds (chemical formula 1) BHETMHETBHEIDEG-ester-1DEG-ester-2ME-esterHA-esterDiemrTrimerExample 10.8698.900.530.000.310.000.010.010.230.01Example 20.4595.760.420.000.000.000.030.003.710.12Example 30.8797.40.740.000.110.010.000.011.670.06Example 40.8490.450.750.000.060.000.010.028.480.23Comparative example 11.8489.251.280.100.400.020.040.008.910.00Comparative example 25.1693.232.940.022.120.050.020.011.480.13Comparative example 31.0594.111.020.010.000.000.020.004.280.56Total content of low molecular weight compounds (formula 1) = MHET+BHEI+DEG-ester-1+DEG-ester-2+ME-ester+HA-ester

[0172] Referring to Table 2 above, it can be confirmed that the raw material compositions of Examples 1 to 4 according to the present invention exhibit high purity with a relatively low peak area ratio of low molecular weight compounds, which are impurities.

[0173]

[0174] [Example 3]

[0175] A BHET-containing composition of 0.5 to 1.0 g was weighed and placed in a vaporizer heated to 150°C, and the vaporized moisture was titrated using the commonly known Karl Fischer method to measure the moisture content of the BHET-containing composition. Based on this, the saturated moisture content and the moisture content change rate over time were calculated, and the results are shown in Table 3 below.

[0176]

[0177] Saturated moisture content (%)Moisture content changeManufacturing date (0 day)After 1 dayAfter 2 daysAfter 4 daysAfter 7 daysAfter 14 daysChange rate over time (△moisture / week)Example 10.330.090.110.190.250.330.320.03Example 20.240.080.140.210.220.240.240.02Example 30.440.090.150.290.410.440.430.05Example 40.350.070.130.250.330.350.340.04Comparative example 13.370.080.511.492.923.373.420.47Comparative example 23.110.091.101.502.873.113.130.43Comparative example 32.410.081.492.122.212.382.390.33

[0178] Referring to Table 3 above, it can be confirmed that the regenerated raw material compositions of Examples 1 to 4 according to the present invention have a very low saturation moisture content of 0.5% or less, and a very low change rate over time of 0.05 or less. This supports the idea that by controlling the crystal form and formulation of BHET included in the regenerated raw material composition, the hygroscopicity of BHET can be significantly reduced.

[0179] On the other hand, the raw material compositions of Comparative Examples 1 to 3 have both a high saturation rate and a high change rate over time, indicating that they contain BHET with high hygroscopicity.

[0180]

[0181] [Example 4]

[0182] About 12.6 cm 2After preparing a sample by placing a 20 g BHET-containing composition on a circular petri dish having an area, a load of about 70,000 Pa was applied on the sample for 4 weeks, and then the occurrence of fusion was evaluated according to the following criteria (whether clumps (caking) were formed), and the results are shown in Table 4 and Figure 4 below.

[0183] ◎: Lump size 2 cm or more,

[0184] ○: Lump size 1 cm or more, less than 2 cm

[0185] ×: No lumps

[0186]

[0187] [Example 5]

[0188] A 100 ml measuring cylinder was filled with a composition containing BHET, the weight was measured, and the weight was divided by the volume of the measuring cylinder, 100 ml, to calculate the apparent density (Bulk Density) (measured weight (g) / 100 ml). The results are shown in Table 5 below.

[0189]

[0190] Whether caking occurs?Total content of low molecular weight compounds (%)Saturated moisture content (%)Example 1×0.860.33Example 2×0.450.24Example 3×0.870.44Example 4×0.840.35Comparative Example 1◎1.843.37Comparative Example 2◎5.163.11Comparative Example 3○1.052.41

[0191] Bulk density (g / ml) Example 10.71 Example 20.65 Example 30.75 Example 40.61 Comparative Example 10.51 Comparative Example 20.54 Comparative Example 30.60

[0192] Referring to Table 4 and Figure 4 above, it can be confirmed that the regenerative raw material compositions of Examples 1 to 4 according to the present invention do not cause fusion and have a low total content of low molecular weight compounds, resulting in a low saturation moisture content. In addition, referring to Table 5 above, it can be confirmed that the apparent density is high and the specific surface area is relatively small.

[0193] On the other hand, it can be confirmed that the recycled raw material compositions of Comparative Examples 1 to 3 have poor handleability due to fusion occurring due to the high total content of low molecular weight compounds and high saturation moisture content. In addition, referring to Table 5 above, it can be seen that the hygroscopicity of BHET will be high because the apparent density is low and the specific surface area is relatively large (wide).

Claims

1. A recycled raw material composition obtained through depolymerization of waste polyester raw material, Contains bis(2-hydroxyethyl)terephthalate (BHET), which is represented by A renewable raw material composition, wherein, when analyzed by X-ray diffraction (XRD), the BHET has a γ crystal form, an α crystal form, or a combination thereof.

2. In paragraph 1, A composition of regenerative raw materials having an apparent density of 0.2 to 0.8 g / ml.

3. In paragraph 1, A regenerative raw material composition having a rate of change in the functional ratio over time of less than 0.3 according to the following formula 1: [Formula 1] The rate of change in the function rate over time = (M7- M0) / 7 In the above equation 1, M7 is the unit-excluding value of the saturation moisture content measured by the Karl Fischer method after storing the above-mentioned raw material composition at room temperature for 7 days. M0 is a numerical value excluding the unit from the initial moisture content measured by the Karl Fischer method for the above-mentioned raw material composition.

4. In paragraph 1, A regenerated raw material composition having a saturation moisture content of less than 1.0% as measured by the Karl Fischer method after storing the above regenerated raw material composition at room temperature for 7 days.

5. In paragraph 1, A regenerative raw material composition having a granular formulation.

6. In paragraph 5, A regenerative raw material composition wherein the shape of the granules is circular or oval.

7. In paragraph 1, A renewable raw material composition, wherein the peak area ratio of a low molecular weight compound represented by the following chemical formula 1 is 20% or less when analyzed by high performance liquid chromatography (HPLC): [Chemical Formula 1] In the above chemical formula 1, R 1 and R 2 are each independently selected from the group consisting of hydrogen, alkyl, hydroxyalkyl, alkylacetate, alkoxyalkyl and aryl, However, in the low molecular weight compound represented by the above chemical formula 1, Bis(2-hydroxyethyl)terephthalate (BHET), which is indicated as , is excluded.

8. In paragraph 1, The γ crystal form of the above BHET has the first largest X-ray diffraction peak (P γ1st ) appears in the 2θ range of 23.0° to 23.9°, and the second largest X-ray diffraction peak (P γ2nd ) appears in the 2θ range of 23.9° to 24.9°, The α crystal form of the above BHET has the first largest X-ray diffraction peak (P α1st ) appears in the 2θ range of 23.0° to 23.9°, and the second largest X-ray diffraction peak (P α2nd ) appears in the 2θ range of 16.1° to 17.0°, a regenerative raw material composition.

9. In paragraph 1, A renewable raw material composition having an SC ratio of the BHET of 1.0 or more according to the following formula 2 when analyzed by the above X-ray diffraction (XRD): [Formula 2] SC ratio = PI max1 / PI max2 In the above equation 2, PI max1 is the intensity of the largest X-ray diffraction peak appearing in the 2θ range of less than 23.0° to 23.9°, PI max2 is the intensity of the largest X-ray diffraction peak appearing in the 2θ range of 18.0° to 20.0°.

10. In paragraph 1, A recycled raw material composition, wherein, in the above X-ray diffraction (XRD) analysis, the BHET exhibits an X-ray diffraction peak with the greatest intensity in the 2θ range of less than 23.0° to 23.9°.

11. In paragraph 1, A recycled raw material composition, wherein, when analyzed by X-ray diffraction (XRD), the BHET does not have a β crystal form or a δ crystal form.

12. In paragraph 1, A renewable raw material composition, wherein the peak area ratio of bis(2-hydroxyethyl)terephthalate (BHET) is 80% or more when analyzed by high-performance liquid chromatography (HPLC). 13.(1) A step of depolymerizing waste polyester raw material to obtain a product; (2) a step of purifying the above product to obtain a liquid purified product; and (3) A step of solidifying the liquid purified product using a granulator is included, Contains bis(2-hydroxyethyl)terephthalate (BHET), which is represented by A method for producing a renewable raw material composition, wherein, when analyzed by X-ray diffraction (XRD), the BHET has a γ crystal form, an α crystal form, or a combination thereof.

14. In paragraph 13, A method for producing a regenerative raw material composition, wherein the above solidification is performed at a temperature of 10 to 100°C.

15. In paragraph 13, A method for producing a recycled raw material composition, wherein depolymerization of the above waste polyester raw material is performed at a temperature of 180 to 220°C for 1 to 30 hours.

16. In paragraph 13, A method for producing a regenerative raw material composition, wherein the above purification comprises a crystallization process of the above product.

17. A recycled polyester resin manufactured from a polymerization raw material comprising the recycled raw material composition of Article 1.

18. A molded product manufactured from the recycled polyester resin of Article 17.

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