Crystalline polyester resin and its manufacturing method

Abstract

The present invention relates to a crystalline polyester resin and a method for preparing the same. The crystalline polyester resin has the crystallinity required for molding and / or recycling processes, while fusion during the preparation process is minimized, allowing it to have excellent productivity, moldability, recyclability, etc.

Description

Detailed Description of the Invention

[0001] [Technical field] The present invention relates to a crystalline polyester resin having excellent moldability and recyclability due to controlled crystallinity, and a method for preparing the crystalline polyester resin.

[0002] [Background technology] Polyester resins are obtained by the polymerization reaction of dicarboxylic acid components and diol components. Because they do not contain substances harmful to the human body and are environmentally friendly, they are widely used in the manufacture of films, partitions, panels, packaging materials, containers, etc. In particular, polyester films prepared using polyester resins have high heat resistance and appropriate heat shrinkage, making them suitable for packaging and / or labeling plastic containers such as PET bottles.

[0003] At the same time, although the use of plastic containers makes our lives more convenient, their indiscriminate disposal or excessive use has caused serious environmental problems. Therefore, various methods have been prepared for recycling waste plastic containers after use.

[0004] Methods for recycling waste plastic containers can be divided into physical recycling processes, which involve washing and crushing, and chemical recycling processes, which involve depolymerization. However, these recycling processes require pretreatment to separate the waste plastics by type, which reduces the efficiency of the recycling process. For example, recycling PET bottles with polyester film attached as labels requires the polyester film to be separated (removed) from the PET bottle. This is due to the difference in crystallinity between the polyester resin contained in the polyester film and the PET components contained in the PET bottle, making the recycling process ineffective when PET bottles with polyester film attached are recycled.

[0005] Therefore, attempts have been made to control the crystallinity of polyester resins to prepare polyester films having a crystallinity close to that of PET bottles. However, there are limitations to optimizing the crystallinity of such polyester resins, and the productivity and processability of crystalline polyester resins are low due to problems such as fusion between polyester resins (e.g., polyester resin pellets) during the process of controlling the crystallinity.

[0006] [DISCLOSURE OF THE INVENTION] [Technical issues] In order to solve the above problems in the prior art, the inventors of the present invention have conducted various studies and found that the crystallinity of a polyester resin can be optimized by controlling the heat of fusion (ΔH) at the melting point of the crystalline polyester resin, thereby obtaining a crystalline polyester resin with excellent productivity, moldability, and recyclability.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a crystalline polyester resin having optimized crystallinity and a method for preparing the same.

[0008] [Solution to the problem] In order to achieve the above object, the present invention provides a crystalline polyester resin comprising diol repeating units derived from a diol component and dicarboxylic acid repeating units derived from a dicarboxylic acid component, wherein the crystalline polyester resin exhibits two or more melting points (T m ) appears, and the following relation 1: [Relationship 1] 4 <X / Y<70 The present invention provides a crystalline polyester resin that satisfies the above requirements.

[0009] In Relationship 1, X is the sum of the heats of fusion (ΔH) at melting points that appear at 200°C or higher, and Y is the sum of the heats of fusion (ΔH) at melting points that appear at less than 200°C.

[0010] The present invention further provides a method for preparing a crystalline polyester resin, the method comprising the steps of: (1) polymerizing a diol component and a dicarboxylic acid component to prepare a polyester resin; and (2) crystallizing the polyester resin one or more times, wherein the crystalline polyester resin exhibits two or more melting points (T m ) appears and satisfies the above relation 1.

[0011] Additionally, the present invention provides articles prepared from the crystalline polyester resins.

[0012] [Advantageous effects of the invention] The present invention can provide a crystalline polyester resin having the crystallinity required for molding (post-treatment) and recycling processes, thereby achieving excellent moldability and recyclability when an article (e.g., an injection-molded article) is prepared from the resin or when the prepared article is recycled.

[0013] Furthermore, since the present invention prepares a crystalline polyester resin through one or more crystallization steps at optimally controlled temperatures in each step, it is possible to minimize the occurrence of fusion between polyester resins during the crystallization steps, thereby improving the productivity and processability of the crystalline polyester resin. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a flow chart showing a procedure for preparing a crystalline polyester resin according to an embodiment of the present invention.

[0015] [Best Mode for Carrying Out the Invention] The present invention will be described in detail below. In this specification, the present invention is not limited to the disclosure shown below, but the present invention may be modified in various forms as long as the gist of the present invention is not changed.

[0016] In the present specification, the term "comprises" is intended to specify certain features, regions, steps, processes, elements, and / or components. Unless specifically stated otherwise, this does not exclude the presence or addition of other features, regions, steps, processes, elements, and / or components.

[0017] Throughout the present specification, terms such as first, second, etc. are used to describe various components, but the components should not be limited by these terms. These terms are used only to distinguish one element from another.

[0018] All numbers and expressions relating to amounts of ingredients, reaction conditions, and the like used herein should be understood as being modified by the term "about" unless otherwise specified.

[0019] Generally, polyester resins prepared by extrusion molding and pelletization such as underwater cutting contain moisture. Therefore, when they are used to mold articles, it is necessary to remove the moisture contained in the polyester resin. If molding is performed without removing the moisture, the quality of the article prepared by molding will deteriorate due to the decrease in polymerization degree caused by hydrolysis reaction due to moisture.

[0020] Therefore, before the polyester resin is supplied to the molding step, a step of drying the polyester resin is carried out to remove the moisture contained in the polyester resin. However, since polyester resins mainly have an amorphous surface, when they are placed in a dryer for drying, they will fuse together or stick to the inner wall of the dryer, which is problematic in that they reduce the drying efficiency and productivity of the polyester resin.

[0021] To solve this problem, attempts have been made to crystallize the polyester resin to prevent melting during the drying procedure, but there are currently limitations in optimizing the crystallinity of polyester resins.

[0022] In particular, if the polyester resin is insufficiently crystallized or, conversely, excessively crystallized, the above-mentioned fusion problem will not be resolved. For example, if excessive crystallization occurs, i.e., if the crystallization temperature is increased, the polyester resin (e.g., polyester resin pellets) will melt between the exothermic and endothermic temperatures, increasing the fusion rate of the polyester resin (the polyester resin pellets will stick together). Furthermore, the processing temperature of crystalline polyester resins requires energy equal to the melting point and the area of ​​the heat of fusion. Because excessively crystallized polyester resins have a fairly high heat of fusion, a large amount of energy is consumed during processing, which reduces their processability in post-processing. Therefore, to improve the moldability of crystalline polyester resins that have undergone a crystallization procedure, it is very important to control the melting point and heat of fusion of the crystalline polyester resin. Furthermore, to improve the recyclability of polyester resins, it is also necessary to optimize the crystallinity of the polyester resin, which can also be achieved by controlling the melting point and heat of fusion of the polyester resin.

[0023] Based on the above, the present invention optimizes the crystallinity of the crystalline polyester resin obtained after crystallization without causing fusion between the polyester resins during the crystallization procedure, thereby ensuring productivity, moldability (processability), and recyclability. For this purpose, the preparation (crystallization) process of the crystalline polyester resin is controlled, while the correlation between the melting point and heat of fusion of the crystalline polyester resin is identified, which will be described in detail below.

[0024] (Crystalline polyester resin) The crystalline polyester resin according to the present invention contains diol repeating units derived from the diol component and dicarboxylic acid repeating units derived from the dicarboxylic acid component, and when the crystalline polyester resin is analyzed by differential scanning calorimetry (DSC) while increasing the temperature up to 280°C at a scan rate of 10°C / min, it exhibits two or more melting points (T m ) appears and satisfies the following relation 1. [Relationship 1] 4 <X / Y<70

[0025] In Relationship 1, X is the sum of the heats of fusion (ΔH) at melting points appearing at 200° C. or higher in DSC analysis, and Y is the sum of the heats of fusion (ΔH) at melting points appearing at less than 200° C. in DSC analysis.

[0026] According to the present invention, when a crystalline polyester resin is analyzed by DSC, two or more (specifically, two or more, three or more, four or more, or 2 to 3) melting points (T m ) appears and satisfies the above relationship 1 based on the specific temperature (melting point) of 200°C; therefore, its crystallinity can be optimized, resulting in excellent moldability and recyclability. The temperature of 200°C is the crystallization temperature (T c ) and melting point (T m ) When this intermediate temperature is used, the amount of heat required for crystallization and post-treatment (melting point) can be optimally controlled.

[0027] Specifically, the ratio of X / Y in Relationship 1 may be 4.1 to 69.9, 4.5 to 69.8, 5 to 69.7, 5.1 to 69.6, 5.3 to 69.5, 5.5 to 69, 5.8 to 68, 6 to 67, 6.3 to 66, 6.5 to 65, 6.8 to 60, 7 to 55, 7.5 to 50, 8 to 45, 8.5 to 40, 9 to 38, or 10 to 35. When the ratio of X / Y is controlled within the above range, a crystalline polyester resin having a desired degree of crystallinity and minimized fusion can be provided.

[0028] According to the present invention, the crystalline polyester resin has two or more melting points (Tm ) may appear in a temperature range of 140 to 245°C. More specifically, two or more melting points (T m ) may be 140 to 243°C, 140 to 242°C, 140 to 240°C, 140.1 to 239.5°C, 140.1 to 239°C, 140.2 to 238.7°C, 140.2 to 238.5°C, 141 to 238.3°C, 142 to 238°C, 145 to 237.5°C, 148 to 237°C, 150 to 236.8°C, 151 to 236.5°C, 153 to 236.3°C, 155 to 236°C, or 158 to 236°C. m ) appears within the above temperature range, a crystalline polyester resin having a desired crystallinity can be provided.

[0029] In a DSC analysis of the crystalline polyester resin according to the present invention, one or more, two or more, or three or more melting points may appear at a temperature below 200°C, and one or more, or two or more melting points may appear at a temperature above 200°C.

[0030] Specifically, in the DSC analysis of the crystalline polyester resin, the first melting point (T m1 ) may occur at temperatures below 200°C, and a second melting point (T m2 ) may appear at temperatures above 200°C. For example, in DSC analysis of a crystalline polyester resin, the first melting point (T m1-1 ) and the first-second melting point (T m1-2 ) may occur at temperatures below 200°C, and a second melting point (T m2 ) may occur at temperatures above 200°C. Specifically, the first-first melting point (T m1-1 ) may be 140 to 198°C, 141 to 195°C, 145 to 193°C, or 150 to 190°C. Specifically, the first and second melting points (T m1-2 ) may be greater than 185°C and up to 210°C, 187 to 205°C, 188 to 200°C, or 189 to 195°C. m2 ) may be greater than 210 to 245°C, 215 to 243°C, 218 to 242°C, or 220 to 240°C.

[0031] According to the present invention, the first melting point (T m1 ) and the second melting point (T m2 ) and the difference (|T m1 -T m2 |) may be 40 to 105°C. Specifically, the difference (|T m1 -T m2 The difference (|T m1 -T m2 In the calculation of the first melting point (T m1 ) is two or more, the lowest melting point among the two or more melting points is referred to as the first melting point (T m1 ) and the second melting point (T m2 ) is two or more, the highest temperature of the two or more melting points is called the second melting point (T m2 ) is judged to be

[0032] According to the present invention, when one or more melting points appear at 200°C or higher during a DSC analysis in which the temperature is increased to 280°C at a scan rate of 10°C / min, X in Relationship 1 is the sum of the heats of fusion (ΔH) at each melting point (ΔH sum1 For example, in DSC analysis, the melting point a (T ma ) and melting point b(T mb ) appear above 200°C, X is the melting point a(T ma ) heat of fusion (ΔH a ) and melting point b(T mb ) heat of fusion (ΔH b ) sum (ΔH a +ΔH b ) where the melting point a (T ma ) appears above 200°C, X is the melting point a(T ma ) heat of fusion (ΔH a) itself. The X value (the sum of the heats of fusion (ΔH) at the melting point appearing at 200°C or higher) is not particularly limited, but may be 20 J / g or more, specifically 20.2 J / g or more, 23 J / g or more, 24 J / g or more, 25 J / g or more, 27 J / g or more, 29 J / g or more, 30 J / g or more, 31 J / g or more, 33 J / g or more, 35 J / g or more, 37 J / g or more, or 40 J / g or more (for example, 20 to 39 J / g, 22 to 38 J / g, 24 to 37 J / g, or 25 to 35 J / g). When the X value is within the above range, a crystalline polyester resin having a desired crystallinity can be provided.

[0033] According to the present invention, in the DSC analysis, when one or more melting points appear below 200°C while the temperature is increased to 280°C at a scan rate of 10°C / min, Y in Relationship 1 is the sum of the heats of fusion (ΔH) at each melting point (ΔH sum2 For example, the melting point c(T mc ) and melting point d(T md ) appear below 200 °C, Y is the melting point c(T mc ) heat of fusion (ΔH c ) and melting point d(T md ) heat of fusion (ΔH d ) sum (ΔH c +ΔH d ) where the melting point c (T mc ) appears at a melting point below 200 °C, Y is the melting point c(T mc ) heat of fusion (ΔH c ) itself. The Y value (the sum of heats of fusion (ΔH) at melting points appearing below 200°C) is not particularly limited, but may be 0.1 to 10 J / g, specifically 0.2 to 9.5 J / g, 0.3 to 9.3 J / g, 0.5 to 9 J / g, 1 to 8.5 J / g, 2.5 to 8 J / g, 3 to 7.8 J / g, 3.3 to 7.5 J / g, 3.5 to 7 J / g, 3.8 to 6.5 J / g, 4 to 6 J / g, 4.2 to 5.8 J / g, or 4.4 to 5.5 J / g. When the Y value is within the above range, a crystalline polyester resin having a desired crystallinity can be provided.

[0034] On the other hand, according to the present invention, the crystalline polyester resin contains a diol repeating unit derived from a diol component. The diol component is not particularly limited as long as it is a commonly known diol component. Specifically, this includes bis-2-hydroxyethyl terephthalate, isosorbide, neopentyl glycol, ethylene glycol, diethylene glycol, cyclohexanedimethanol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-methylene-1,3-propanediol, 2-ethyl-1,3-propanediol, 2-isopropyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 1,4-butanediol, 2,3-butanediol, 3-methyl-1,5-pentanediol, 3-methyl-2,4-pentanediol, 1,6-hexanediol, 1,2-cyclohexanediol, 1 The regenerated cyclohexane dimethanol may comprise at least one (e.g., two or more, three or more, four or more, or five or more) selected from the group consisting of 4-cyclohexanediol, 4-(hydroxymethyl)cyclohexylmethyl-4-(hydroxymethyl)cyclohexanecarboxylate (CHDM derivative), 4-(4-(hydroxymethyl)cyclohexylmethoxymethyl)cyclohexylmethanol (CHDM derivative), 2,2,4,4-tetramethyl-1,3-cyclobutanediol (TMCD), recycled bis-2-hydroxyethyl terephthalate, recycled isosorbide, recycled neopentyl glycol, recycled ethylene glycol, recycled diethylene glycol, and recycled cyclohexanedimethanol.

[0035] Here, the recycled bis-2-hydroxyethyl terephthalate, recycled isosorbide, recycled neopentyl glycol, recycled ethylene glycol, recycled diethylene glycol, and recycled cyclohexanedimethanol used as the diol component can refer to recycled raw materials (monomers) obtained by subjecting waste polyester resins or post-consumer waste polyester articles to a commonly known depolymerization process, but are not limited to these.

[0036] More specifically, the diol component may comprise at least one selected from the group consisting of: a first diol component comprising ethylene glycol (EG), recycled ethylene glycol (r-EG), or a combination thereof; a second diol component comprising bis-2-hydroxyethyl terephthalate (BHET), recycled bis-2-hydroxyethyl terephthalate (r-BHET), or a combination thereof; and a third diol component comprising isosorbide (ISB), neopentyl glycol (NPG), diethylene glycol (DEG), cyclohexanedimethanol (CHDM), recycled isosorbide (r-ISB), recycled neopentyl glycol (r-NPG), recycled diethylene glycol (r-DEG), recycled cyclohexanedimethanol (r-CHDM), or a combination thereof.

[0037] The amount of the first diol component used (the amount added to the reaction) is not particularly limited, but may be 50 to 99 mol%, 60 to 99 mol%, 70 to 99 mol%, 70 to 98 mol%, 75 to 98 mol%, 75 to 97 mol%, or 80 to 90 mol% based on the total mole percent of the diol components. Therefore, the crystalline polyester resin may contain a repeating unit (a) derived from the first diol component. When the amount of the first diol component used is within the above range, a crystalline polyester resin with excellent basic physical properties can be produced economically.

[0038] The amount of the second diol component used (the amount added to the reaction) is not particularly limited, but may be 5 to 99 mol%, 5.5 to 95 mol%, 10 to 90 mol%, 15 to 80 mol%, 20 to 80 mol%, 25 to 75 mol%, or 30 to 70 mol% based on the total mole percent of the diol components. Therefore, the crystalline polyester resin may contain repeating units (b) derived from the second diol component. When the amount of the second diol component used is within the above range, it is possible to prepare a crystalline polyester resin with the viscosity required for the molding process. As a result, it is possible to provide an article (molded article) of excellent quality.

[0039] The amount of the third diol component used (the amount added to the reaction) is not particularly limited, but may be 20 mol% or less based on the total mol% of the diol components. Specifically, the amount of the third diol component used may be 1 to 20 mol%, 2 to 20 mol%, 2.5 to 19 mol%, 3 to 18 mol%, 3 to 17.5 mol%, 4 to 17 mol%, 4 to 16 mol%, or 4.5 to 15 mol% based on the total mol% of the diol components. Therefore, the crystalline polyester resin may contain a repeating unit (c) derived from the third diol component. When the amount of the third diol component used is within the above range, a crystalline polyester resin having excellent moldability (processability) and excellent basic physical properties can be produced.

[0040] For example, taking into consideration the basic physical properties and moldability (processability) of the crystalline polyester resin, the amount of isosorbide or recycled isosorbide used in the third diol component may be 0-8 mol%, 0.1-6 mol%, 0.3-4 mol%, or 0.4-3.5 mol% based on the total mole percent of the diol components. Furthermore, the amount of diethylene glycol or recycled diethylene glycol used in the third diol component may be 0.5-10 mol%, 1-7 mol%, 1.5-5 mol%, or 2-4 mol% based on the total mole percent of the diol components. Furthermore, the amount of cyclohexanedimethanol or recycled cyclohexanedimethanol used in the third diol component may be 0-14 mol%, 1-12 mol%, 2-10 mol%, or 3-9 mol% based on the total mole percent of the diol components.

[0041] According to the present invention, the crystalline polyester resin contains dicarboxylic acid repeating units derived from a dicarboxylic acid component. The dicarboxylic acid component is not particularly limited as long as it is a commonly known dicarboxylic acid component. Specifically, it may include at least one selected from the group consisting of terephthalic acid, isophthalic acid, dimethyl phthalate, dimethyl isophthalate, dimethyl terephthalate, phthalic acid, phthalic anhydride, 2,6-naphthalenedicarboxylic acid, dimethyl 2,6-naphthalenedicarboxylate, diphenyldicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, dimethyl 1,4-cyclohexanedicarboxylate, dimethyl 1,3-cyclohexanedicarboxylate, sebacic acid, succinic acid, isodecyl succinic acid, maleic acid, maleic anhydride, fumaric acid, adipic acid, glutaric acid, azelaic acid, recycled terephthalic acid, recycled dimethyl terephthalate, recycled isophthalic acid, and recycled phthalic acid.

[0042] Here, the recycled terephthalic acid, recycled dimethyl terephthalate, recycled isophthalic acid, and recycled phthalic acid used as the dicarboxylic acid component can refer to recycled raw materials (monomers) obtained by subjecting waste polyester resins or post-consumer waste polyester articles to a generally known depolymerization process, but are not limited to these.

[0043] More specifically, the dicarboxylic acid component may comprise at least one selected from the group consisting of a first dicarboxylic acid component comprising terephthalic acid (TPA), dimethyl phthalate, dimethyl isophthalate, dimethyl terephthalate (DMT), recycled terephthalic acid (r-TPA), recycled dimethyl terephthalate (r-DMT), or a combination thereof; and a second dicarboxylic acid component comprising isophthalic acid, phthalic acid, phthalic anhydride, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, dimethyl 1,4-cyclohexanedicarboxylate, dimethyl 1,3-cyclohexanedicarboxylate, recycled isophthalic acid, recycled phthalic acid, or a combination thereof.

[0044] The amount of the first dicarboxylic acid component used (the amount added to the reaction) is not particularly limited, but may be 95 mol% or more, 96 mol% or more, 97 mol% or more, 98 mol% or more, or 99 mol% or more (e.g., 95 to 100 mol%, more than 95 to 100 mol%, 96 to 99.5 mol%, 97 to 99 mol%, or 98 to 98.5 mol%) based on the total mole percent of the dicarboxylic acid components. Thus, the crystalline polyester resin may contain repeating units (z) derived from the first dicarboxylic acid component.

[0045] The amount of the second dicarboxylic acid component used (the amount added to the reaction) is not particularly limited, but may be 5 mol% or less, 4 mol% or less, 3 mol% or less, 2 mol% or less, or 1 mol% or less (e.g., 0 to 5 mol%, more than 0 to 4.5 mol%, 0.5 to 4 mol%, 1 to 3 mol%, or 1.5 to 2 mol%) based on the total mole percent of the dicarboxylic acid components. Thus, the crystalline polyester resin may contain repeating units (w) derived from the second dicarboxylic acid component.

[0046] The crystalline polyester resin according to the present invention may further contain a repeating unit (A) derived from a branching agent having three or more functional groups. Thanks to the branching agent, the repeating unit (A) is introduced into a side chain of the main chain or a graft polymerization structure is formed by the repeating unit (A), so that the crystalline polyester resin can have a high molecular weight and a high degree of crystallinity.

[0047] According to the present invention, the content of the repeating unit (A) contained in the crystalline polyester resin is not particularly limited, but may be 0.001 to 15 wt %, 0.005 to 13 wt %, 0.01 to 12 wt %, 0.02 to 10 wt %, or 0.03 to 5 wt % based on the total weight percent of the diol repeating units.

[0048] The branching agent is not particularly limited, but may specifically be trimellitic acid, trimellitic anhydride, trimethylolpropane, or a combination thereof.

[0049] According to the present invention, the crystalline polyester resin may have an intrinsic viscosity (IV) (at 35° C.) of 0.5 to 1.3 dl / g. Specifically, the intrinsic viscosity (IV) of the crystalline polyester resin at 35° C. may be 0.51 to 1.3 dl / g, 0.53 to 1.29 dl / g, 0.56 to 1.28 dl / g, 0.56 to 1.27 dl / g, 0.59 to 1.25 dl / g, or 0.6 to 1.25 dl / g.

[0050] According to the present invention, the crystalline polyester resin may have a fusion ratio of 5% or less, as determined by the following relationship 2. Specifically, the fusion ratio of the crystalline polyester resin may be 4.8% or less, 4.6% or less, 4.5% or less, 4.3% or less, 4% or less, 3.8% or less, 3.5% or less, 3.3% or less, 3% or less, 2.5% or less, 2.3% or less, 2% or less, 1.8% or less, 1.5% or less, 1% or less, 0.8% or less, 0.5% or less, 0.3% or less, or 0.1% or less (e.g., 0.001 to 5%, 0.005 to 4%, 0.01 to 3%, or 0.1 to 2%). As a result, the productivity of the crystalline polyester resin is very high, while ensuring moldability (processability) during the molding process of the crystalline polyester resin. [Relationship 2] Fusion ratio (%) = (W F / W T ) x 100

[0051] In relation 2, W T is the total weight of crystalline polyester resin produced per unit time (1 hour), and W F is the weight of fused material produced per ton of crystalline polyester resin produced.

[0052] Fused material is material that cannot pass through a vibrator with a mesh of 12.5 mm.

[0053] The crystalline polyester resin according to the present invention may be in the form of chips, pellets, or powder.

[0054] Furthermore, the crystalline polyester resin according to the present invention may be a homopolymer or a copolymer. Specifically, the crystalline polyester resin may be selected from the group consisting of polyethylene terephthalate (PET), polyethylene terephthalate glycol (PETG), polyester sulfone (PES), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polybutylene adipate-co-terephthalate (PBAT), polypropylene adipate-co-terephthalate (PPAT), polycyclohexanedimethylterephthalate (PCT), and thermoplastic polyester elastomer (TPEE).

[0055] (Method for preparing crystalline polyester resin) The method for preparing a crystalline polyester resin according to the present invention includes the steps of: (1) polymerizing a diol component and a dicarboxylic acid component to prepare a polyester resin; and (2) crystallizing the polyester resin one or more times. When the crystalline polyester resin prepared by steps (1) and (2) is analyzed by differential scanning calorimetry (DSC) while increasing the temperature to 280°C at a scan rate of 10°C / min, it exhibits two or more melting points (T m ) appears, satisfying the following relationship 1. The method for preparing a crystalline polyester resin according to the present invention is characterized in that the crystallization temperature is controlled stepwise in step (2). By controlling the crystallization degree so as to satisfy the following relationship 1, it is possible to prepare a crystalline polyester resin with excellent moldability and recyclability. This will be explained in detail below with reference to FIG. 1. Here, the explanation of the following relationship 1 is the same as that described above, and therefore will be omitted. [Relationship 1] 4 <X / Y<70

[0056] In Relationship 1, X is the sum of the heats of fusion (ΔH) at melting points that appear at 200°C or higher, and Y is the sum of the heats of fusion (ΔH) at melting points that appear at less than 200°C.

[0057] [Step (1): Preparation of polyester resin] Step (1) is a step of esterifying (or transesterifying) a diol component and a dicarboxylic acid component to obtain a reactant (e.g., an oligomer), which is then subjected to a polycondensation reaction to prepare a polyester resin (e.g., a polyester resin having a non-crystalline surface). Here, the diol component and the dicarboxylic acid component are the same as those described above, so detailed description thereof will be omitted.

[0058] The conditions for carrying out the esterification reaction (or transesterification reaction) are not particularly limited. Specifically, the temperature for carrying out the esterification reaction may be 220 to 300°C, 225 to 290°C, 230 to 280°C, 235 to 275°C, 240 to 270°C, or 245 to 265°C. Furthermore, the pressure for carrying out the esterification reaction may be 0.05 to 5 kgf / cm. 2 , 0.1~4kgf / cm 2 , 0.1~3kgf / cm 2 , 0.5~2.5kgf / cm 2 , or 1 to 2 kgf / cm 2 When the esterification reaction is carried out under the above conditions, the production of side reactants is minimized, while a reactant (oligomer) having a desired molecular weight can be obtained in high yield.

[0059] In addition to the diol component and the dicarboxylic acid component, at least one additive selected from the group consisting of a catalyst, a colorant, a crystallization agent, an antioxidant, and a branching agent may be fed to the reactor in which the esterification reaction (or transesterification reaction) is carried out.

[0060] The catalyst may be sodium and magnesium methylates; acetates, borates, fatty acid salts, or carbonates of Ge, Zn, Cd, Mn, Co, Ca, and Ba; and oxides or hydrates of Ge, Mg, Pb, Mn, Ti, Sb, Sn, and Al. For example, the catalyst may be tetraethyl titanate, acetyltripropyl titanate, tetrapropyl titanate, tetrabutyl titanate, 2-ethylhexyl titanate, octylene glycol titanate, triethanolamine titanate, acetylacetonate titanate, ethylacetoacetate titanate, isostearyl titanate, titanium dioxide, germanium dioxide, germanium tetrachloride, germanium ethyleneglycoside, germanium acetate, or a combination thereof.

[0061] As the colorant, organic compounds such as cobalt compounds, anthraquinone compounds, perinone compounds, azo compounds, and methine compounds (e.g., cobalt acetate, cobalt propionate, Clariant's Polysynthren Blue RLS toner, and Clariant's Solvaperm Red BB toner) may be used.

[0062] As the crystallizing agent, a crystal nucleating agent, an ultraviolet absorber, a polyolefin resin, a polyamide resin, or the like may be used.

[0063] As the antioxidant, a hindered phenol compound, a phosphite compound, a thioether compound, or the like may be used.

[0064] The branching agent may be trimellitic acid, trimellitic anhydride, trimethylolpropane, or a combination thereof, as described above.

[0065] The reaction product obtained by the esterification reaction (or transesterification reaction) may then be supplied to a polycondensation reactor to carry out a polycondensation reaction. The conditions for carrying out the polycondensation reaction are not particularly limited. Specifically, the temperature for carrying out the polycondensation reaction may be 240 to 320°C, 245 to 310°C, 250 to 300°C, 255 to 295°C, or 265 to 290°C. Furthermore, the pressure for carrying out the polycondensation reaction may be a pressure (reduced pressure) lower than normal pressure (for example, 1 atm). When the polycondensation reaction is carried out under the above conditions, a polyester resin (polymer) having excellent moldability (processability) can be efficiently produced.

[0066] Thereafter, the polyester resin obtained by the polycondensation reaction may be pelletized by a procedure such as extrusion molding and underwater cutting, that is, the polyester resin may be polyester resin pellets.

[0067] The polyester resin (e.g., polyester resin pellets) obtained in the above step (1) may be subjected to the following step (2) so as to have a desired crystallinity. Here, the polyester resin may be subjected to a drying process before the following step (2) is performed. That is, the method for preparing a crystalline polyester resin according to the present invention may further include a step of drying the polyester resin obtained in step (1) between steps (1) and (2) in order to further optimize the crystallinity of the crystalline polyester resin while preventing fusion between the polyester resins.

[0068] The polyester resin may be dried using a conventionally known dryer (for example, a fluidized bed dryer). The drying conditions are not particularly limited, but when considering the drying efficiency and productivity of the polyester resin, drying may be performed at 40 to 90°C (specifically, 40 to 85°C, 45 to 85°C, 50 to 80°C, or 50 to 70°C) for 3 to 12 hours (specifically, 4 to 12 hours or 5 to 11 hours).

[0069] [Step (2): Preparation of crystalline polyester resin by crystallization] Step (2) is a step of crystallizing the polyester resin obtained in step (1) one or more times. Specifically, the crystallization of the polyester resin may be carried out two or more times, three or more times, or four or more times.

[0070] According to the present invention, the temperature at which crystallization is carried out is not particularly limited, but may be 105 to 185 °C (specifically, 106 to 184 °C, 107 to 183 °C, 108 to 182 °C, 109 to 181 °C, or 110 to 180 °C). When crystallization is carried out within the above range, a crystalline polyester resin having an optimized degree of crystallinity can be prepared while minimizing the fusion between polyester resins during the crystallization procedure.

[0071] Furthermore, according to the present invention, crystallization may be carried out under temperature conditions that increase step by step. Specifically, when crystallization is carried out in the first and second stages, the second crystallization temperature (T2) may be higher than the first crystallization temperature (T1) (T1 < T2). Furthermore, when crystallization is carried out in the first to third stages, the third crystallization temperature (T3) may be higher than the second crystallization temperature (T2), and the second crystallization temperature (T2) may be higher than the first crystallization temperature (T1) (T1 < T2 < T3). When crystallization is carried out under temperature conditions that increase step by step, a crystalline polyester resin having an optimized degree of crystallinity can be prepared while minimizing the fusion between polyester resins during the crystallization procedure.

[0072] According to the present invention, step (2) may specifically include: (2-1) a first crystallization step of the polyester resin of step (1) at 105 to 135°C (specifically, 108 to 133°C or 110 to 130°C); (2-2) a second crystallization step of the polyester resin crystallized in step (2-1) at 120 to 175°C (specifically, 120 to 170°C or 125 to 155°C); and (2-3) a third crystallization step of the polyester resin crystallized in step (2-2) at 140 to 180°C (specifically, 145 to 180°C or 150 to 180°C). When the crystallization is performed in three stages and each crystallization temperature is controlled within the above-mentioned specific range, crystals are formed uniformly inside and outside the polyester resin, while at the same time, fusion between polyester resins caused by surface melting during the crystallization procedure can be minimized. Therefore, polyester resins having optimized crystallinity can be efficiently prepared (through improved productivity), thereby realizing crystalline polyester resins with excellent moldability and recyclability.

[0073] Here, the first crystallization temperature, the second crystallization temperature, and the third crystallization temperature may be different from each other.

[0074] The crystallization may be carried out under atmospheric or reduced pressure conditions. A commonly known fluidizing agent may be added to the crystallization procedure to increase the fluidity of the polyester resin (polyester resin pellets).

[0075] The crystalline polyester resin prepared by the crystallization in step (2) as described above may be further subjected to a generally known solid-state polymerization procedure, if necessary, to control the viscosity and molecular weight.

[0076] (Goods) The article according to the present invention is prepared from the above-mentioned crystalline polyester resin. Specifically, the article according to the present invention can be prepared by subjecting the crystalline polyester resin to a molding process such as injection molding, extrusion molding, extrusion blow molding, injection blow molding, pressure molding, or vacuum molding. For example, the article may be an injection-molded article prepared by injection molding.

[0077] Since the article is prepared from the above-mentioned crystalline polyester resin, it can have excellent qualities (for example, heat resistance, mechanical strength, appearance, etc.) Furthermore, since the article is prepared from the above-mentioned crystalline polyester resin, when the recycling process is carried out after the end of use, the efficiency of the recycling process can also be excellent.

[0078] The article is not particularly limited, and may be a film; a sheet; or a small or large container (for example, a container for cosmetics, food, etc.).

[0079] [Mode of Invention] The present invention will be described in more detail below with reference to embodiments, but these examples are provided for illustrative purposes only and the present invention is not limited thereto.

[0080] [Example 1] [Step (1): Preparation of polyester resin] A reactor equipped with a column and a water-cooled condenser was charged with recycled bis-2-hydroxyethyl terephthalate (r-BHET, 2,515.3 kg), terephthalic acid (TPA, 6,575.6 kg), isosorbide (ISB, 309.8 kg), ethylene glycol (EG, 2,624.5 kg), 1,4-cyclohexanedimethanol (CHDM, 633.8 kg), diethylene glycol (DEG, 70.0 kg), Ge catalyst (1.0 kg), Ti catalyst (1.0 kg), phosphoric acid (1.5 kg), blue toner (0.01 kg), and red toner (0.005 kg). The reactor temperature was then increased to 265°C, and the pressure was increased to 2 kgf / cm at 265°C. 2The esterification reaction (ES) was carried out under a pressure of 1000kJ / min to give a transparent reaction product.

[0081] The reactants were then transferred to a polycondensation reactor, where a polycondensation reaction (PA) was carried out at 270°C while maintaining the pressure in the polycondensation reactor at a pressure lower than atmospheric pressure. When the intrinsic viscosity (melt intrinsic viscosity) (IV) of the reactants in the polycondensation reactor reached 0.60 dL / g, the reactants were discharged to the outside of the polycondensation reactor to form strands. These were then solidified with a cooling liquid and pelletized so that the average weight of 100 pellets was approximately 1.0 to 2.5 g, thereby obtaining polyester resin pellets.

[0082] The polyester resin pellets thus obtained were then dried at 50°C for 10 hours before being crystallized.

[0083] [Step (2): Crystallization of Polyester Resin] The dried polyester resin pellets were fed into a crystallization reactor at a rate of 1 ton / hour (feed rate: 1 ton / hour), and the crystallization procedure was carried out three times while increasing the temperature according to the movement position of the polyester resin pellets, thereby obtaining a crystalline polyester resin. In such an event, the first crystallization of the polyester resin pellets was carried out at 110°C, the second crystallization of the first crystallized polyester resin pellets was carried out at 130°C, and the third crystallization of the second crystallized polyester resin pellets was carried out at 165°C.

[0084] [Example 2] [Step (1): Preparation of polyester resin] A reactor equipped with a column and a condenser capable of being cooled with water was charged with terephthalic acid (TPA, 8,462.5 kg), ethylene glycol (EG, 4,874.5 kg), 1,4-cyclohexanedimethanol (CHDM, 326.3 kg), diethylene glycol (DEG, 72.1 kg), Ti catalyst (1.0 kg), phosphoric acid (1.5 kg), blue toner (0.01 kg), and red toner (0.01 kg). The temperature of the reactor was then increased to 255°C, and the pressure was increased to 1 kgf / cm at 255°C.2 The esterification reaction (ES) was carried out under a pressure of 1000kJ / min to give a transparent reaction product.

[0085] The reactants were then transferred to a polycondensation reactor, where a polycondensation reaction (PA) was carried out at 285°C while maintaining the pressure in the polycondensation reactor at a pressure lower than atmospheric pressure. When the intrinsic viscosity (melt intrinsic viscosity) (IV) of the reactants in the polycondensation reactor reached 0.50 dL / g, the reactants were discharged outside the polycondensation reactor to form strands. These were then solidified with a cooling liquid and pelletized so that the average weight of 100 pellets was approximately 1.0 to 2.5 g, thereby obtaining polyester resin pellets.

[0086] [Step (2): Crystallization of Polyester Resin] The polyester resin pellets (undried) were fed into a crystallization reactor at a rate of 1 ton / hour (feed rate: 1 ton / hour), and the crystallization procedure was carried out three times while increasing the temperature according to the movement position of the polyester resin pellets, thereby obtaining a crystalline polyester resin. In such an event, the first crystallization of the polyester resin pellets was carried out at 115°C, the second crystallization of the first crystallized polyester resin pellets was carried out at 120°C, and the third crystallization of the second crystallized polyester resin pellets was carried out at 160°C.

[0087] [Example 3] [Step (1): Preparation of polyester resin] A reactor equipped with a column and a water-cooled condenser was charged with recycled bis-2-hydroxyethyl terephthalate (r-BHET, 6,569.4 kg), terephthalic acid (TPA, 8,157.5 kg), isophthalic acid (IPA, 429.3 kg), ethylene glycol (EG, 2,180.8 kg), diethylene glycol (DEG, 109.7 kg), Ge catalyst (1.0 kg), and phosphoric acid (1.5 kg). The reactor temperature was then increased to 260°C, and the pressure was increased to 1 kgf / cm at 260°C. 2 The esterification reaction (ES) was carried out under a pressure of 1000kJ / min to give a transparent reaction product.

[0088] The reactants were then transferred to a polycondensation reactor, where a polycondensation reaction (PA) was carried out at 275°C while maintaining the pressure in the polycondensation reactor at a pressure lower than atmospheric pressure. When the intrinsic viscosity (melt intrinsic viscosity) (IV) of the reactants in the polycondensation reactor reached 0.78 dL / g, the reactants were discharged to the outside of the polycondensation reactor to form strands. These were then solidified with a cooling liquid and pelletized so that the average weight of 100 pellets was approximately 1.0 to 2.5 g, thereby obtaining polyester resin pellets.

[0089] The polyester resin pellets thus obtained were then dried at 40° C. for 9 hours before being crystallized.

[0090] [Step (2): Crystallization of Polyester Resin] The dried polyester resin pellets were fed into a crystallization reactor at a rate of 1 ton / hour (feed rate: 1 ton / hour), and the crystallization procedure was carried out three times while increasing the temperature according to the movement position of the polyester resin pellets, thereby obtaining a crystalline polyester resin. In such an event, the first crystallization of the polyester resin pellets was carried out at 120°C, the second crystallization of the first crystallized polyester resin pellets was carried out at 135°C, and the third crystallization of the second crystallized polyester resin pellets was carried out at 150°C.

[0091] [Example 4] [Step (1): Preparation of polyester resin] A reactor equipped with a column and a water-cooled condenser was charged with recycled bis-2-hydroxyethyl terephthalate (r-BHET, 5,125.6 kg), terephthalic acid (TPA, 5,024.7 kg), isosorbide (ISB, 52.6 kg), ethylene glycol (EG, 2,229.7 kg), 1,4-cyclohexanedimethanol (CHDM, 484.3 kg), diethylene glycol (DEG, 71.3 kg), Ge catalyst (1.0 kg), phosphoric acid (1.5 kg), cobalt acetate (0.4 kg), blue toner (0.03 kg), and red toner (0.01 kg). The reactor temperature was then increased to 250°C, and the pressure was increased to 1 kgf / cm at 250°C. 2 The esterification reaction (ES) was carried out under a pressure of 1000kJ / min to give a transparent reaction product.

[0092] The reactants were then transferred to a polycondensation reactor, where a polycondensation reaction (PA) was carried out at 285°C while maintaining the pressure in the polycondensation reactor at a pressure lower than atmospheric pressure. When the intrinsic viscosity (melt intrinsic viscosity) (IV) of the reactants in the polycondensation reactor reached 0.85 dL / g, the reactants were discharged to the outside of the polycondensation reactor to form strands. These were then solidified with a cooling liquid and pelletized so that the average weight of 100 pellets was approximately 1.0 to 2.5 g, thereby obtaining polyester resin pellets.

[0093] [Step (2): Crystallization of Polyester Resin] The polyester resin pellets (undried) were fed into a crystallization reactor at a rate of 1 ton / hour (feed rate: 1 ton / hour), and the crystallization procedure was carried out three times while increasing the temperature according to the movement position of the polyester resin pellets, thereby obtaining a crystalline polyester resin. In such an event, the first crystallization of the polyester resin pellets was carried out at 110°C, the second crystallization of the first crystallized polyester resin pellets was carried out at 170°C, and the third crystallization of the second crystallized polyester resin pellets was carried out at 180°C.

[0094] [Example 5] [Step (1): Preparation of polyester resin] Polyester resin pellets were obtained by the same procedure as in Example 1. The polyester resin pellets thus obtained were then dried at 55°C for 4 hours before being crystallized.

[0095] [Step (2): Crystallization of Polyester Resin] The dried polyester resin pellets were fed into a crystallization reactor at a rate of 1 ton / hour (feed rate: 1 ton / hour), and the crystallization procedure was carried out three times while increasing the temperature according to the movement position of the polyester resin pellets, thereby obtaining a crystalline polyester resin. In such an event, the first crystallization of the polyester resin pellets was carried out at 125°C, the second crystallization of the first crystallized polyester resin pellets was carried out at 130°C, and the third crystallization of the second crystallized polyester resin pellets was carried out at 140°C.

[0096] [Example 6] [Step (1): Preparation of polyester resin] Polyester resin pellets were obtained in the same manner as in Example 3.

[0097] [Step (2): Crystallization of Polyester Resin] The polyester resin pellets (undried) were fed into a crystallization reactor at a rate of 1 ton / hour (feed rate: 1 ton / hour), and the crystallization procedure was carried out three times while increasing the temperature according to the movement position of the polyester resin pellets, thereby obtaining a crystalline polyester resin. In such an event, the first crystallization of the polyester resin pellets was carried out at 130°C, the second crystallization of the first crystallized polyester resin pellets was carried out at 150°C, and the third crystallization of the second crystallized polyester resin pellets was carried out at 180°C.

[0098] [Comparative Example 1] [Step (1): Preparation of polyester resin] Polyester resin pellets were obtained in the same manner as in Example 3.

[0099] [Step (2): Crystallization of Polyester Resin] The polyester resin pellets (undried) were fed into a crystallization reactor at a rate of 1 ton / hour (feed rate: 1 ton / hour), and the crystallization procedure was carried out three times while decreasing the temperature according to the movement position of the polyester resin pellets, thereby obtaining a crystalline polyester resin. In such an event, the first crystallization of the polyester resin pellets was carried out at 160°C, the second crystallization of the first crystallized polyester resin pellets was carried out at 140°C, and the third crystallization of the second crystallized polyester resin pellets was carried out at 120°C.

[0100] Comparative Example 2 [Step (1): Preparation of polyester resin] Polyester resin pellets were obtained by the same procedure as in Example 3. The polyester resin pellets thus obtained were then dried at 55°C for 3 hours before being crystallized.

[0101] [Step (2): Crystallization of Polyester Resin] The dried polyester resin pellets were fed into a crystallization reactor at a rate of 1 ton / hour (feed rate: 1 ton / hour), and the crystallization procedure was carried out three times while increasing the temperature according to the movement position of the polyester resin pellets, thereby obtaining a crystalline polyester resin. In such an event, the first crystallization of the polyester resin pellets was carried out at 140°C, the second crystallization of the first crystallized polyester resin pellets was carried out at 160°C, and the third crystallization of the second crystallized polyester resin pellets was carried out at 200°C.

[0102] Comparative Example 3 [Step (1): Preparation of polyester resin] Polyester resin pellets were obtained in the same manner as in Example 4.

[0103] [Step (2): Crystallization of Polyester Resin] The polyester resin pellets (undried) were fed into a crystallization reactor at a rate of 1 ton / hour (feed rate: 1 ton / hour), and the crystallization procedure was carried out while increasing the temperature according to the movement position of the polyester resin pellets, thereby obtaining a crystalline polyester resin. In such an event, the first crystallization of the polyester resin pellets was carried out at 100°C, the second crystallization of the first crystallized polyester resin pellets was carried out at 160°C, and the third crystallization of the second crystallized polyester resin pellets was carried out at 190°C.

[0104] Comparative Example 4 [Step (1): Preparation of polyester resin] Polyester resin pellets were obtained in the same manner as in Example 1.

[0105] [Step (2): Crystallization of Polyester Resin] The polyester resin pellets (undried) were fed into a crystallization reactor at a rate of 1 ton / hour (feed rate: 1 ton / hour), and the crystallization procedure was carried out once at 170°C, thereby obtaining a crystalline polyester resin.

[0106] Comparative Example 5 [Step (1): Preparation of polyester resin] Polyester resin pellets were obtained by the same procedure as in Example 3. The polyester resin pellets thus obtained were then dried at 40°C for 3 hours before being crystallized.

[0107] [Step (2): Crystallization of Polyester Resin] The dried polyester resin pellets were fed into a crystallization reactor at a rate of 1 ton / hour (feed rate: 1 ton / hour), and the crystallization procedure was carried out twice while increasing the temperature according to the movement position of the polyester resin pellets, thereby obtaining a crystalline polyester resin. In such an event, the first crystallization of the polyester resin pellets was carried out at 70°C, and the second crystallization of the first crystallized polyester resin pellets was carried out at 160°C.

[0108] [Test Example 1] The crystalline polyester resins prepared in Examples 1 to 6 and Comparative Examples 1 to 5 were analyzed by differential scanning calorimetry (DSC) to determine their melting points (T m The results are shown in Tables 1 and 2 below. DSC analysis was carried out as follows.

[0109] DSC analysis device: DSC 1 model manufactured by Mettler Toledo was used.

[0110] Sample preparation: Approximately 6 to 10 mg of each crystalline polyester resin was taken and placed in an aluminum dish.

[0111] Scanning conditions: This was heated from room temperature to 280°C at a rate of 10°C / min, followed by annealing at 280°C for 3 minutes to obtain a DSC curve.

[0112] Melting point (T m ) Determination: In the DSC curve obtained, the temperature at which an endothermic peak appeared during the temperature increase procedure was determined as the melting point. m ) was used to calculate the heat of fusion (ΔH) and the X / Y ratio (rounded to two decimal places).

[0113] [Test Example 2] The weight of fused material (kg) produced per ton of total production (kg / hour) was measured and then the fusion rate was calculated according to the following relationship 2. The results are shown in Tables 1 and 2 below. [Relationship 2] Fusion ratio (%) = (W F / W T ) x 100

[0114] In relation 2, W T is the total weight (total production amount) of crystalline polyester resin produced per unit time (1 hour), and W F is the weight of fused material produced per ton of crystalline polyester resin produced (to separate the total production amount into 1-ton samples, the weight of fused material contained in each sample was measured).

[0115] The fused material (polyester resin fused material) is a material that cannot pass through a vibrator with a mesh of 12.5 mm.

[0116] [Test Example 3] The crystalline polyester resins prepared in Examples 1 to 6 and Comparative Examples 1 to 5 were each injection molded at a temperature of 250 to 260°C using an ENGEL 25 device to prepare injection-molded samples having a length of 100 mm, a width of 100 mm, and a thickness of 3 mm. The moldability of these samples was evaluated according to the following criteria. The results are shown in Tables 1 and 2 below. ◎: There were no fish eyes or unmelted areas (resin pellets not melted) in the injection molding sample, and a continuous injection process was possible. 〇: There was no unmelted material in the injection molded sample, there was one or less fish eye, and a continuous injection process was possible. △: There were two or more unmelted areas and fish eyes in the injection molded sample, but a continuous injection process was possible ×: Fusion occurred between the resin pellets, making continuous injection process impossible.

[0117] [Table 1]

[0118] [Table 2]

[0119] Referring to Table 1 above, the crystalline polyester resins of Examples 1 to 6 according to the present invention had a very low fusion ratio of 5% or less during the crystallization procedure and an X / Y ratio controlled within the range of the present invention, thereby exhibiting excellent productivity and moldability together with an optimized crystallinity.

[0120] In contrast, referring to Table 2 above, the crystalline polyester resin of Comparative Example 1, which was crystallized under stepwise temperature reduction conditions, and the crystalline polyester resins of Comparative Examples 2 and 3, which had crystallization temperatures outside the range of the present invention, had a fusion ratio of more than 5%, resulting in insufficient productivity of the crystalline polyester resin. Furthermore, in Comparative Examples 1 to 3, excessive crystallization caused fish eyes and unmelted portions during the injection molding process, resulting in insufficient moldability. Furthermore, the crystalline polyester resin of Comparative Example 4, which was crystallized once at a low temperature, and the crystalline polyester resin of Comparative Example 5, which was crystallized twice (showing translucency due to insufficient crystallization), had a very high fusion ratio during the crystallization procedure, making crystallization impossible or insufficient. Furthermore, in Comparative Example 5, fusion occurred between the crystalline polyester resin molecules, resulting in insufficient moldability.

Claims

1. A crystalline polyester resin comprising a diol repeating unit derived from a diol component and a dicarboxylic acid repeating unit derived from a dicarboxylic acid component, wherein the crystalline polyester resin exhibits two or more melting points (T ｍ ) appears, and the following relationship 1 [Relationship 1] 4<X / Y<70 wherein in Relationship 1, X is the sum of heats of fusion (ΔH) at the melting points appearing at 200°C or higher, and Y is the sum of heats of fusion (ΔH) at the melting points appearing at lower than 200°C.

2. The melting point (T ｍ 2. The crystalline polyester resin according to claim 1, wherein the melting point of the crystalline polyester resin is 140 to 245°C.

3. In the DSC analysis of the crystalline polyester resin, a first melting point (T ｍ１ ) appears at temperatures below 200°C, and a second melting point (T ｍ２ ) appears at temperatures above 200°C, The first melting point (T ｍ１ ) and the second melting point (T ｍ２ ) and the difference (|T ｍ１ -T ｍ２ 2. The crystalline polyester resin according to claim 1, wherein the temperature (Tc) is 40 to 105°C.

4. The crystalline polyester resin according to claim 1, wherein the sum (X) of heats of fusion (ΔH) at the melting points appearing at 200° C. or higher is 20 J / g or higher.

5. 2. The crystalline polyester resin according to claim 1, wherein the total (Y) of heats of fusion (ΔH) at the melting points appearing below 200° C. is 0.1 to 10 J / g.

6. The crystalline polyester resin according to claim 1, wherein the dicarboxylic acid component comprises at least one selected from the group consisting of terephthalic acid, isophthalic acid, dimethyl phthalate, dimethyl isophthalate, dimethyl terephthalate, phthalic acid, phthalic anhydride, 2,6-naphthalenedicarboxylic acid, dimethyl 2,6-naphthalenedicarboxylate, diphenyldicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, dimethyl 1,4-cyclohexanedicarboxylate, dimethyl 1,3-cyclohexanedicarboxylate, sebacic acid, succinic acid, isodecyl succinic acid, maleic acid, maleic anhydride, fumaric acid, adipic acid, glutaric acid, azelaic acid, recycled terephthalic acid, recycled dimethyl terephthalate, recycled isophthalic acid, and recycled phthalic acid.

7. 2. The crystalline polyester resin of claim 1, wherein the dicarboxylic acid component comprises at least one selected from the group consisting of: a first dicarboxylic acid component comprising terephthalic acid, dimethyl phthalate, dimethyl isophthalate, dimethyl terephthalate, recycled terephthalic acid, recycled dimethyl terephthalate, or a combination thereof; and a second dicarboxylic acid component comprising isophthalic acid, phthalic acid, phthalic anhydride, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, dimethyl 1,4-cyclohexanedicarboxylate, dimethyl 1,3-cyclohexanedicarboxylate, recycled isophthalic acid, recycled phthalic acid, or a combination thereof.

8. 8. The crystalline polyester resin of claim 7, wherein the amount of the second dicarboxylic acid component used is 5 mole percent or less, based on the total mole percent of the dicarboxylic acid components.

9. The diol component is bis-2-hydroxyethyl terephthalate, isosorbide, neopentyl glycol, ethylene glycol, diethylene glycol, cyclohexanedimethanol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-methylene-1,3-propanediol, 2-ethyl-1,3-propanediol, 2-isopropyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 1,4-butanediol, 2,3-butanediol, 3-methyl-1,5-pentanediol, 3-methyl-2,4-pentanediol, or 1,6-hexanediol , 1,2-cyclohexanediol, 1,4-cyclohexanediol, 4-(hydroxymethyl)cyclohexylmethyl-4-(hydroxymethyl)cyclohexanecarboxylate, 4-(4-(hydroxymethyl)cyclohexylmethoxymethyl)cyclohexylmethanol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, regenerated bis-2-hydroxyethyl terephthalate, regenerated isosorbide, regenerated neopentyl glycol, regenerated ethylene glycol, regenerated diethylene glycol, and regenerated cyclohexanedimethanol. The crystalline polyester resin of claim 1, comprising at least one selected from the group consisting of:

10. 2. The crystalline polyester resin of claim 1, wherein the diol component comprises at least one selected from the group consisting of: a first diol component comprising ethylene glycol, recycled ethylene glycol, or a combination thereof; a second diol component comprising bis-2-hydroxyethyl terephthalate, recycled bis-2-hydroxyethyl terephthalate, or a combination thereof; and a third diol component comprising isosorbide, neopentyl glycol, diethylene glycol, cyclohexanedimethanol, regenerated isosorbide, regenerated neopentyl glycol, regenerated diethylene glycol, regenerated cyclohexanedimethanol, or a combination thereof.

11. 11. The crystalline polyester resin of claim 10, wherein the amount of the third diol component used is 20 mole percent or less, based on the total mole percent of the diol components.

12. The following relationship 2: [Relationship 2] Fusion ratio (%) = (W Ｆ / W Ｔ ) x 100 The fusion ratio by W is 5% or less, and in relation 2, Ｔ is the total weight of the crystalline polyester resin produced per unit time (1 hour), and W Ｆ is the weight of fused material produced per ton of the crystalline polyester resin produced, and the fused material is material that cannot pass through a vibrator having a mesh of 12.5 mm.

13. The crystalline polyester resin according to claim 1 , further comprising a repeating unit derived from a branching agent having three or more functional groups.

14. 14. The crystalline polyester resin of claim 13, wherein the content of the repeat units derived from the branching agent is 0.001 to 15 weight percent based on the total weight percent of the diol repeat units.

15. 2. The crystalline polyester resin of claim 1, having an intrinsic viscosity (IV) of 0.5 to 1.3 dl / g.

16. (1) polymerizing a diol component and a dicarboxylic acid component to prepare a polyester resin; (2) crystallizing the polyester resin one or more times; 1. A method for preparing a crystalline polyester resin comprising: When the crystalline polyester resin was analyzed by differential scanning calorimetry (DSC) at a scan rate of 10°C / min, increasing the temperature to 280°C, it was found to have two or more melting points (T ｍ ) appears, and the following relation 1: [Relationship 1] 4<X / Y<70 In the relationship 1, X is the sum of the heats of fusion (ΔH) at the melting points appearing at 200°C or higher, and Y is the sum of the heats of fusion (ΔH) at the melting points appearing at less than 200°C.

17. 17. The method for preparing a crystalline polyester resin according to claim 16, wherein the crystallization in step (2) is carried out at a temperature in the range of 105 to 185°C.

18. 17. The method for preparing a crystalline polyester resin according to claim 16, wherein the crystallization in step (2) is carried out under stepwise increasing temperature conditions.

19. 17. A method for preparing the crystalline polyester resin of claim 16, wherein step (2) comprises: (2-1) performing a first crystallization of the polyester resin of step (1) at 105 to 135°C; (2-2) performing a second crystallization at 120 to 175°C on the polyester resin crystallized in step (2-1); (2-3) performing a third crystallization at 140 to 180°C on the polyester resin crystallized in step (2-2); A method comprising:

20. 17. The method for preparing the crystalline polyester resin of claim 16, further comprising the step of drying the polyester resin obtained in step (1) before step (2) is carried out.

21. An article prepared from the crystalline polyester resin of any one of claims 1 to 15.

22. 22. The article of claim 21, wherein the article is an injection molded article.

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