Crystalline polyester resin and method for producing same

Abstract

The invention relates to crystalline polyester resin and a preparation method thereof. Since the crystalline polyester resin has a degree of crystallinity required in a molding process and / or a recovery process while minimizing melting in a preparation process, it may have excellent productivity, plasticity, recoverability, and the like.

Description

Technical Field

[0001] 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. Background Art

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

[0003] At the same time, the use of plastic containers has brought convenience to real life, but due to random discarding or excessive use, environmental problems are becoming increasingly serious. Therefore, various methods for recycling used plastic containers are being developed.

[0004] The recycling process of waste plastic containers can be divided into a physical recycling process through cleaning and crushing and a chemical recycling process through a depolymerization process. However, in order to carry out such a recycling process, a pre-processing operation of separating waste plastics by plastic type is required, which reduces the efficiency of the recycling process. For example, in order to recycle PET bottles with polyester films attached as labels, an operation of separating (removing) the polyester films from the PET bottles must be carried out. This is due to the difference in crystallinity between the polyester resin contained in the polyester film and the PET component contained in the PET bottle, which makes it impossible to carry out the recycling process when the PET bottles with polyester films attached are recycled.

[0005] Therefore, attempts have been made to control the crystallinity of polyester resins to prepare polyester films having similar crystallinity to that of PET bottles. However, there are limits to optimizing the crystallinity of such polyester resins, and since problems such as melting may occur between polyester resins (e.g., polyester resin pellets) during the process of controlling the crystallinity, the productivity and processability of crystalline polyester resins are low. Summary of the invention

[0006] Technical issues

[0007] In order to solve the above problems in the prior art, the present inventors have conducted various studies and found that by controlling the melting heat (ΔH) at the melting temperature of the crystalline polyester resin, the crystallinity of the polyester resin can be optimized, thereby obtaining a crystalline polyester resin with excellent productivity, plasticity and recyclability.

[0008] Therefore, an object of the present invention is to provide a crystalline polyester resin having optimized crystallinity and a method for preparing the same.

[0009] Solution to the problem

[0010] In order to achieve the above object, the present invention provides 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 when the crystalline polyester resin is analyzed by differential scanning calorimetry (DSC), when the temperature is increased to 280°C at a scanning rate of 10°C / min, two or more melting temperatures (T m ), and satisfy the following relationship 1:

[0011] [Equation 1]

[0012] 4 <X / Y<70

[0013] In Relational Formula 1, X is the sum of the heat of fusion (ΔH) occurring at a melting temperature of 200°C or higher, and Y is the sum of the heat of fusion (ΔH) occurring at a melting temperature of less than 200°C.

[0014] In addition, the present invention provides a method for preparing a crystalline polyester resin, which comprises (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 when the crystalline polyester resin is analyzed by differential scanning calorimetry (DSC), when the temperature is increased to 280° C. at a scanning rate of 10° C. / min, two or more melting temperatures (T m ), and the above relationship 1 is satisfied.

[0015] Furthermore, the present invention provides an article prepared from the crystalline polyester resin.

[0016] Advantageous Effects of the Invention

[0017] The present invention can provide a crystalline polyester resin having the desired crystallinity in the molding (post-processing) process and the recycling process. Therefore, when an article (such as an injection-molded article) is prepared therefrom or the prepared article is recycled, excellent plasticity and recyclability can be achieved.

[0018] In addition, since the present invention prepares the crystalline polyester resin through one or more crystallization steps, and the crystallization is performed at an optimally controlled temperature in each step, the occurrence of melting between the polyester resins in the crystallization step can be minimized. As a result, the productivity and processability of the crystalline polyester resin can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a flow chart for preparing a crystalline polyester resin according to one embodiment of the present invention. DETAILED DESCRIPTION

[0020] Best Mode for Carrying Out the Invention

[0021] The present invention will be described in detail below. The present invention is not limited to the disclosure given below, but can be modified into various forms as long as the gist of the present invention is not changed.

[0022] In this specification, the term "comprising" is intended to specify specific features, regions, steps, methods, elements and / or components. Unless otherwise expressly stated, the existence or addition of any other features, regions, steps, methods, elements and / or components is not excluded.

[0023] Throughout this specification, the terms first, second, etc. are used to describe various components. However, these components should not be limited by these terms. These terms are used to distinguish one element from another.

[0024] Unless otherwise indicated, all numbers and expressions relating to quantities of ingredients, reaction conditions, and so forth used herein are to be understood as modified by the term "about."

[0025] Generally, polyester resins prepared by extrusion and granulation, such as underwater cutting, contain moisture. Therefore, when it is used to form a product, it is necessary to remove the moisture contained in the polyester resin. If molding is performed without removing moisture, the degree of polymerization is reduced due to the hydrolysis reaction of moisture, so the quality of the product prepared by molding is deteriorated.

[0026] Therefore, before the polyester resin is supplied to the molding process, a process of drying the polyester resin is performed to remove the moisture contained in the polyester resin. However, the polyester resin mainly has an amorphous surface; therefore, there is a problem that when they are put into a dryer for drying, they are fused to each other or adhere to the inner wall of the dryer, which reduces the drying efficiency and productivity of the polyester resin.

[0027] To address this problem, attempts have been made to crystallize the polyester resin to prevent melting during the drying process. However, there are currently limitations to optimizing the crystallinity of polyester resins.

[0028] In particular, if the crystallization of the polyester resin is insufficient, or conversely, if it is over-crystallized, the above-mentioned melting problem will not be solved. For example, when over-crystallization occurs, that is, when the crystallization temperature rises, the melting of the polyester resin (e.g., polyester resin pellets) occurs between the exothermic temperature and the endothermic temperature, and the melting rate of the polyester resin increases (the polyester resin particles adhere to each other). In addition, the processing temperature of the polyester resin with crystallinity requires an area equivalent to the melting temperature and the energy of the melting heat. Since the excessively crystallized polyester resin has a relatively high melting heat, a large amount of energy is consumed during the processing, which reduces the processability in the post-processing. Therefore, in order to improve the plasticity of the crystalline polyester resin that has undergone the crystallization process, it is very important to control the melting temperature and the melting heat of the crystalline polyester resin. In addition, in order to increase the recyclability of the polyester resin, it is also necessary to optimize the crystallinity of the polyester resin, which can also be achieved by controlling the melting temperature and the melting heat of the polyester resin.

[0029] In summary, the present invention optimizes the crystallinity of the crystalline polyester resin obtained after crystallization without causing melting between the polyester resins during the crystallization process, thereby ensuring productivity, plasticity (processability) and recyclability. For this purpose, it is characterized in that the preparation (crystallization) process of the crystalline polyester resin is controlled while specifying the correlation between the melting temperature and the melting heat of the crystalline polyester resin, which will be explained in detail below.

[0030] Crystalline polyester resin

[0031] The crystalline polyester resin according to the present invention comprises a diol repeating unit derived from a diol component; and a dicarboxylic acid repeating unit derived from a dicarboxylic acid component, wherein when the crystalline polyester resin is analyzed by differential scanning calorimetry (DSC), when the temperature is increased to 280°C at a scanning rate of 10°C / min, two or more melting temperatures (T m ), and satisfies the following relation 1.

[0032] [Equation 1]

[0033] 4 <X / Y<70

[0034] In Relational Formula 1, X is the sum of the heat of fusion (ΔH) appearing at a melting temperature of 200° C. or higher in DSC analysis, and Y is the sum of the heat of fusion (ΔH) appearing at a melting temperature of less than 200° C. in DSC analysis.

[0035] According to the present invention, when the crystalline polyester resin is analyzed by DSC, two or more (specifically, two or more, three or more, four or more, or two to three) melting temperatures (T m), and based on the specific temperature (melting temperature) 200°C satisfies the above relationship 1; therefore, its crystallinity can be optimized, thereby having excellent plasticity and recyclability. The temperature of 200°C may refer to the crystallization temperature (T c ) and melting temperature (T m When the intermediate temperature is used, the heat required for crystallization and post-processing (melting temperature) can be optimally controlled.

[0036] Specifically, the X / Y ratio in Relational Formula 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 X / Y ratio is controlled within the above range, a crystalline polyester resin having a desired crystallinity can be provided while minimizing melting.

[0037] According to the present invention, in the crystalline polyester resin, two or more melting temperatures (T m ) can range from 140°C to 245°C. More specifically, two or more melting temperatures (T m ) can be 140°C to 243°C, 140°C to 242°C, 140°C to 240°C, 140.1°C to 239.5°C, 140.1°C to 239°C, 140.2°C to 238.7°C, 140.2°C to 238.5°C, 141°C to 238.3°C, 142°C to 238°C, 145°C to 237.5°C, 148°C to 237°C, 150°C to 236.8°C, 151°C to 236.5°C, 153°C to 236.3°C, 155°C to 236°C, or 158°C to 236°C. When two or more melting temperatures (T m ) occurs within the above temperature range, a crystalline polyester resin having a desired degree of crystallinity can be provided.

[0038] In the DSC analysis of the crystalline polyester resin of the present invention, one or more, two or more, or three or more melting temperatures may appear at a temperature below 200°C, and one or more, or two or more melting temperatures may appear at a temperature of 200°C or higher.

[0039] Specifically, in the DSC analysis of the crystalline polyester resin, the first melting temperature (T m1 ) may occur at temperatures below 200°C, and the second melting temperature (T m2) may appear at a temperature of 200°C or higher. For example, in the DSC analysis of a crystalline polyester resin, the first-first melting temperature (T m1-1 ) may occur at temperatures below 200°C, and the first-second melting temperature (T m1-2 ) may occur at a temperature of 200°C or higher. Specifically, the first-first melting temperature (T m1-1 ) may be 140°C to 198°C, 141°C to 195°C, 145°C to 193°C, or 150°C to 190°C. Specifically, the first-second melting temperature (T m1-2 ) may be higher than 185°C to 210°C, 187°C to 205°C, 188°C to 200°C, or 189°C to 195°C. Specifically, the second melting temperature (T m2 ) may be above 210°C to 245°C, 215°C to 243°C, 218°C to 242°C, or 220°C to 240°C.

[0040] According to the present invention, the first melting temperature (T m1 ) and the second melting temperature (T m2 ) between (|T m1 -T m2 |) may be 40°C to 105°C. Specifically, the difference (|T m1 -T m2 |) may be 43°C to 105°C, 45°C to 103°C, 48°C to 103°C, 50°C to 101°C, 52°C to 99°C, 54°C to 98.8°C, 54.5°C to 98.5°C, 55°C to 95°C, 56°C to 93°C, 57°C to 90°C, 57.5°C to 85°C, 58°C to 80°C, 59°C to 75°C, or 60°C to 70°C. In calculating the difference (|T m1 -T m2 |), when the first melting temperature (T m1 ) when there are two or more melting temperatures, the lowest melting temperature among the two or more melting temperatures is regarded as the first melting temperature (T m1 ), when the second melting temperature (T m2 ) when there are two or more melting temperatures, the highest temperature among the two or more melting temperatures is regarded as the second melting temperature (T m2 ).

[0041] According to the present invention, when the temperature is raised to 280°C at a scanning rate of 10°C / min in DSC analysis, when one or more melting temperatures appear at 200°C or higher, X in Relational Formula 1 may refer to the sum (ΔH) of the heat of fusion (ΔH) at the respective melting temperatures. 总和1 For example, if the melting temperature a(T ma ) and melting temperature b(Tmb ) these two melting temperatures appear at 200°C or higher, then X can be at the melting temperature a(T ma ) under the melting heat (ΔH a ) and at the melting temperature b(T mb ) under the melting heat (ΔH b ) (ΔH a +ΔH b ). If the melting temperature a(T ma ) has a melting temperature of 200°C or higher, then X can be the melting temperature a(T ma ) under the melting heat (ΔH a ) itself. The X value (the sum of the heat of fusion (ΔH) at a melting temperature occurring 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 (e.g., 20 J / g to 39 J / g, 22 J / g to 38 J / g, 24 J / g to 37 J / g, or 25 J / g to 35 J / g). When the value of X is within the above range, a crystalline polyester resin having a desired degree of crystallinity can be provided.

[0042] According to the present invention, when the temperature is increased to 280°C at a scanning rate of 10°C / min in DSC analysis, when one or more melting temperatures appear below 200°C, Y in Relational Formula 1 may refer to the sum (ΔH) of the heat of fusion (ΔH) at each melting temperature. 总和2 For example, if the melting temperature c(T mc ) and melting temperature d(T md ) these two melting temperatures appear below 200°C, then Y can be at the melting temperature c(T mc ) under the melting heat (ΔH c ) and at the melting temperature d(T md ) under the heat of fusion (ΔH d ) (ΔH c +ΔH d ). If the melting temperature c(T mc ) has a melting temperature below 200°C, then Y can be the melting temperature c(T mc ) under the heat of fusion (ΔH c) itself. The Y value (the sum of the heat of fusion (ΔH) at the melting temperature occurring at a temperature lower than 200° C.) is not particularly limited, but may be 0.1 J / g to 10 J / g, specifically, 0.2 J / g to 9.5 J / g, 0.3 J / g to 9.3 J / g, 0.5 J / g to 9 J / g, 1 J / g to 8.5 J / g, 2.5 J / g to 8 J / g, 3 J / g to 7.8 J / g, 3.3 J / g to 7.5 J / g, 3.5 J / g to 7 J / g, 3.8 J / g to 6.5 J / g, 4 J / g to 6 J / g, 4.2 J / g to 5.8 J / g, or 4.4 J / g to 5.5 J / g. When the value of Y is within the above range, a crystalline polyester resin having a desired degree of crystallinity may be provided.

[0043] Meanwhile, according to the present invention, the crystalline polyester resin comprises a diol repeating unit derived from a diol component. As a diol component, there is no particular limitation as long as it is a well-known diol component. Specifically, it may include a diol selected from bis-2-hydroxyethyl terephthalate, isosorbide, neopentyl glycol, ethylene glycol, diethylene glycol, cyclohexanedimethanol, 1,2-propylene glycol, 1,3-propylene glycol, 2-methyl-1,3-propylene glycol, 2-methylene-1,3-propylene glycol, 2-ethyl-1,3-propylene glycol, 2-isopropyl-1,3-propylene glycol, 2,2-dimethyl-1,3-propylene glycol, 1,4-butanediol, 2,3-butanediol, 3-methyl-1,5-pentanediol, 3-methyl-2,4-pentanediol, 1,6-hexanediol, 1,2-cyclohexanediol, 1 , 4-cyclohexanediol, 4-(hydroxymethyl)cyclohexylmethyl-4-(hydroxymethyl)cyclohexanecarboxylate (CHDM derivative), 4-(4-(hydroxymethyl)cyclohexylmethoxymethyl)cyclohexylmethanol (CHDM derivative), 2,2,4,4-tetramethyl-1,3-cyclobutanediol (TMCD), recovered bis-2-hydroxyethyl terephthalate, recovered isosorbide, recovered neopentyl glycol, recovered ethylene glycol, recovered diethylene glycol, and recovered cyclohexanedimethanol. At least one of the group (for example, 2 or more, 3 or more, 4 or more, or 5 or more).

[0044] Here, the recovered bis-2-hydroxyethyl terephthalate, recovered isosorbide, recovered neopentyl glycol, recovered ethylene glycol, recovered diethylene glycol and recovered cyclohexanedimethanol used as the diol component may refer to recovered raw materials (monomers) obtained by subjecting used waste polyester resins or waste polyester products to a known depolymerization process, but they are not limited thereto.

[0045] More specifically, the diol component may include at least one selected from the group consisting of a first diol component including ethylene glycol (EG), recycled ethylene glycol (r-EG), or a combination thereof; a second diol component including bis-2-hydroxyethyl terephthalate (BHET), recycled bis-2-hydroxyethyl terephthalate (r-BHET), or a combination thereof; and a third diol component including 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.

[0046] The amount of the first diol component (the amount added in the reaction) is not particularly limited, but it can be 50 mol% to 99 mol%, 60 mol% to 99 mol%, 70 mol% to 99 mol%, 70 mol% to 98 mol%, 75 mol% to 98 mol%, 75 mol% to 97 mol%, or 80 mol% to 90 mol% based on the total molar percentage of the diol component. Therefore, the crystalline polyester resin may include repeating units (a) derived from the first diol component. When the amount of the first diol component is within the above range, a crystalline polyester resin having excellent basic physical properties can be economically produced.

[0047] The amount of the second diol component (the amount added in the reaction) is not particularly limited, but the total molar percentage thereof based on the diol component may be 5 mol% to 99 mol%, 5.5 mol% to 95 mol%, 10 mol% to 90 mol%, 15 mol% to 80 mol%, 20 mol% to 80 mol%, 25 mol% to 75 mol% or 30 mol% to 70 mol%. Therefore, the crystalline polyester resin may contain repeating units (b) derived from the second diol component. When the amount of the second diol component is within the above range, a crystalline polyester resin having a desired viscosity level during molding can be prepared. Therefore, a product (molded product) of excellent quality can be provided.

[0048] The amount of the third glycol component (the amount added in the reaction) is not particularly limited, but relative to the total molar percentage of the glycol component, it can be 20 mol% or less. Specifically, the amount of the third glycol component can be 1 mol% to 20 mol%, 2 mol% to 20 mol%, 2.5 mol% to 19 mol%, 3 mol% to 18 mol%, 3 mol% to 17.5 mol%, 4 mol% to 17 mol%, 4 mol% to 16 mol% or 4.5 mol% to 15 mol%. Therefore, the crystalline polyester resin can include repeating units (c) derived from the third glycol component. When the amount of the third glycol component is within the above range, a crystalline polyester resin with excellent basic physical properties and excellent plasticity (processability) can be produced.

[0049] For example, when considering the basic physical properties and plasticity (processability) of the crystalline polyester resin, the amount of isosorbide or recovered isosorbide in the third glycol component can be 0 mol% to 8 mol%, 0.1 mol% to 6 mol%, 0.3 mol% to 4 mol%, or 0.4 mol% to 3.5 mol%, based on the total mole percentage of the glycol component. In addition, the amount of diethylene glycol or recovered diethylene glycol used in the third glycol component can be 0.5 mol% to 10 mol%, 1 mol% to 7 mol%, 1.5 mol% to 5 mol%, or 2 mol% to 4 mol%, based on the total mole percentage of the glycol component. In addition, the amount of cyclohexanedimethanol or recovered cyclohexanedimethanol in the third glycol component can be 0 mol% to 14 mol%, 1 mol% to 12 mol%, 2 mol% to 10 mol%, or 3 mol% to 9 mol%, based on the total mole percentage of the glycol component.

[0050] According to the present invention, the crystalline polyester resin includes a dicarboxylic acid repeating unit derived from a dicarboxylic acid component. The dicarboxylic acid component is not particularly limited as long as it is a known dicarboxylic acid component. Specifically, it may contain 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-naphthalene dicarboxylic acid, dimethyl 2,6-naphthalene dicarboxylate, diphthalic acid, 1,4-cyclohexane dicarboxylic acid, dimethyl 1,3-cyclohexane dicarboxylate, 1,4-cyclohexane dicarboxylic acid, dimethyl 1,3-cyclohexane dicarboxylate, 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.

[0051] Here, the recovered terephthalic acid, recovered dimethyl terephthalate, recovered isophthalic acid, and recovered phthalic acid as dicarboxylic acid components may refer to recovered raw materials (monomers) obtained by subjecting used waste polyester resins or waste polyester products to a known depolymerization treatment, but they are not limited thereto.

[0052] More specifically, the dicarboxylic acid component may include 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.

[0053] The amount of the first dicarboxylic acid component used (the amount added in the reaction) is not particularly limited, but it 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 mol% to 100 mol%, greater than 95 mol% to 100 mol%, 96 mol% to 99.5 mol%, 97 mol% to 99 mol%, or 98 mol% to 98.5 mol%) based on the total molar percentage of the dicarboxylic acid component. Thus, the crystalline polyester resin may contain a repeating unit (z) derived from the first dicarboxylic acid component.

[0054] The amount of the second dicarboxylic acid component (the amount added in the reaction) is not particularly limited, but it 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 mol% to 5 mol%, greater than 0 mol% to 4.5 mol%, 0.5 mol% to 4 mol%, 1 mol% to 3 mol%, or 1.5 mol% to 2 mol%) based on the total molar percentage of the dicarboxylic acid component. Thus, the crystalline polyester resin may contain a repeating unit (w) derived from the second dicarboxylic acid component.

[0055] The crystalline polyester resin according to the present invention may further contain a repeating unit (A) derived from a branching agent having 3 or more functional groups. Due to the branching agent, when the repeating unit (A) is introduced into the side chain of the main chain, or a grafted polymer structure is formed by the repeating unit (A), the crystalline polyester resin may have a high molecular weight and high crystallinity.

[0056] 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 percentage of the diol repeating units.

[0057] The branching agent is not particularly limited, but specifically may be trimellitic acid, trimellitic anhydride, trimethylolpropane, or a combination thereof.

[0058] According to the present invention, the crystalline polyester resin may have an intrinsic viscosity (IV) of 0.5 dl / g to 1.3 dl / g (at 35° C.). Specifically, the intrinsic viscosity (IV) of the crystalline polyester resin at 35° C. may be 0.51 dl / g to 1.3 dl / g, 0.53 dl / g to 1.29 dl / g, 0.56 dl / g to 1.28 dl / g, 0.56 dl / g to 1.27 dl / g, 0.59 dl / g to 1.25 dl / g, or 0.6 dl / g to 1.25 dl / g.

[0059] According to the present invention, the crystalline polyester resin may have a melting rate of 5% or less according to the following relational formula 2. Specifically, the melting rate 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 excellent, and plasticity (processability) can be ensured during the molding process of the crystalline polyester resin.

[0060] [Equation 2]

[0061] Melting rate (%) = (W F / W T )×100

[0062] In equation 2, W T is the total weight of the crystalline polyester resin produced per unit time (1 hour), and W F It is the weight of molten material produced per ton of crystalline polyester resin produced.

[0063] The molten material is a material that cannot pass through a vibrator having a mesh opening of 12.5 mm.

[0064] The crystalline polyester resin according to the present invention may be in the form (shape) of chips, pellets or powder.

[0065] In addition, the crystalline polyester resin according to the present invention can be a homopolymer or a copolymer. Specifically, the crystalline polyester resin can be selected from the group consisting of polyethylene terephthalate (PET), polyethylene terephthalate (PETG), polyester sulfone (PES), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polybutylene adipate-terephthalate (PBAT), polytrimethylene adipate-terephthalate (PPAT), polycyclohexane dicarboxylate (PCT), and thermoplastic polyester elastomer (TPEE).

[0066] Method for preparing crystalline polyester resin

[0067] According to the method for preparing a crystalline polyester resin of the present invention, it comprises (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 when the crystalline polyester resin prepared by the steps (1) and (2) is analyzed by differential scanning calorimetry (DSC), when the temperature is increased to 280° C. at a scanning rate of 10° C. / min, two or more melting temperatures (T m ), and the following relational expression 1 is satisfied. The method for preparing a crystalline polyester resin according to the present invention is characterized in that the crystallization temperature is gradually controlled in step (2). By controlling to satisfy the following relational expression 1, a crystalline polyester resin having excellent plasticity and recyclability can be prepared. Figure 1 This is described in detail. Wherein, the description of the following relational expression 1 is the same as that described above, and thus will be omitted.

[0068] [Equation 1]

[0069] 4 <X / Y<70

[0070] In Relational Formula 1, X is the sum of the heat of fusion (ΔH) occurring at a melting temperature of 200°C or higher, and Y is the sum of the heat of fusion (ΔH) occurring at a melting temperature of less than 200°C.

[0071] Step (1): Preparation of polyester resin

[0072] Step (1) is to subject the diol component and the dicarboxylic acid component to an esterification reaction (or an ester exchange reaction) 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). Since the diol component and the dicarboxylic acid component are the same as described above, a detailed description thereof is omitted.

[0073] The conditions for carrying out the esterification reaction (or transesterification reaction) may not be particularly limited. Specifically, the temperature for carrying out the esterification reaction may be 220° C. to 300° C., 225° C. to 290° C., 230° C. to 280° C., 235° C. to 275° C., 240° C. to 270° C., or 245° C. to 265° C. In addition, the pressure for carrying out the esterification reaction may be 0.05 kgf / cm 2 Up to 5kgf / cm 2 、0.1kgf / cm 2 Up to 4kgf / cm 2 、0.1kgf / cm 2 Up to 3kgf / cm 2 、0.5kgf / cm 2 Up to 2.5kgf / cm 2 , or 1kgf / cm 2 Up to 2kgf / cm 2When the esterification reaction is carried out under the above conditions, the generation of side reactants is minimized, while reactants (oligomers) having a desired molecular weight can be obtained in high yield.

[0074] 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 crystallizing agent, an antioxidant, and a branching agent may be fed into the reactor for conducting the esterification reaction (or transesterification reaction).

[0075] The catalyst may be a methylate of sodium and magnesium; an acetate, borate, fatty acid salt or carbonate of Ge, Zn, Cd, Mn, Co, Ca and Ba; and an oxide or hydrate of Ge, Mg, Pb, Mn, Ti, Sb, Sn and Al. For example, the catalyst may include tetraethyl titanate, acetyl tripropyl titanate, tetrapropyl titanate, tetrabutyl titanate, 2-ethylhexyl titanate, octanediol titanate, triethanolamine titanate, acetylacetonate titanate, ethyl acetoacetate titanate, isostearyl titanate, titanium dioxide, germanium dioxide, germanium tetrachloride, ethylene glycol germanium, germanium acetate or a combination thereof.

[0076] As the colorant, organic compounds such as cobalt-based compounds, anthraquinone-based compounds, cyclic ketone-based compounds, azo-based compounds and methine compounds can be used (e.g., cobalt acetate, cobalt propionate, Clariant's Polysynthren Blue RLS, Clariant's Solvaperm Red BB toner can be used).

[0077] As the crystallizing agent, a crystal nucleating agent, an ultraviolet absorber, a polyolefin resin, a polyamide resin, etc. can be used.

[0078] As the antioxidant, hindered phenol-based compounds, phosphite-based compounds, thioether-based compounds, and the like can be used.

[0079] As the branching agent, trimellitic acid, trimellitic anhydride, trimethylolpropane or a combination thereof as described above may be used.

[0080] The reactant obtained by esterification (or transesterification) can then be fed to a polycondensation reactor to carry out a polycondensation reaction. The conditions for carrying out the polycondensation reaction may not be particularly limited. Specifically, the temperature for carrying out the polycondensation reaction may be 240°C to 320°C, 245°C to 310°C, 250°C to 300°C, 255°C to 295°C or 265°C to 290°C. In addition, the pressure for carrying out the polycondensation reaction may be lower (decompressed) than normal pressure (e.g., 1atm). By carrying out the polycondensation reaction under the above conditions, a polyester resin (polymer) having excellent plasticity (processability) can be effectively manufactured.

[0081] Subsequently, the polyester resin obtained by the polycondensation reaction may be made into pellets by extrusion, underwater cutting, etc. That is, the polyester resin may be polyester resin pellets.

[0082] The polyester resin (e.g., polyester resin particles) obtained by the above step (1) may be subjected to the following step (2) to have a desired crystallinity. The polyester resin may be subjected to a drying process before the following step (2). 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 step (1) and step (2), thereby further optimizing the crystallinity of the crystalline polyester resin while preventing melting between the polyester resins.

[0083] The polyester resin may be dried in a conventionally known dryer (e.g., a fluidized bed dryer). The drying conditions are not particularly limited, but in consideration of the drying efficiency and productivity of the polyester resin, the polyester resin may be dried at 40° C. to 90° C. (specifically, 40° C. to 85° C., 45° C. to 85° C., 50° C. to 80° C., or 50° C. to 70° C.) for 3 to 12 hours (specifically, 4 to 12 hours or 5 to 11 hours).

[0084] Step (2): Preparation of crystalline polyester resin by crystallization method

[0085] 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 performed two or more times, three or more times, or four or more times.

[0086] According to the present invention, the temperature at which crystallization is performed is not particularly limited, but may be 105° C. to 185° C. (specifically, 106° C. to 184° C., 107° C. to 183° C., 108° C. to 182° C., 109° C. to 181° C., or 110° C. to 180° C.). When crystallization is performed within the above range, a crystalline polyester resin having optimized crystallinity can be prepared while minimizing melting between polyester resins during the crystallization process.

[0087] In addition, according to the present invention, crystallization can be carried out under gradually increasing temperature conditions. Specifically, when crystallization is carried out in the first stage and the second stage, the second crystallization temperature (T2) can be higher than the first crystallization temperature (T1) (T1 < T2). In addition, when crystallization is carried out in the first to third stages, the third crystallization temperature (T3) can be higher than the second crystallization temperature (T2), and the second crystallization temperature (T2) can be higher than the first crystallization temperature (T1) (T1 < T2 < T3). When crystallization is carried out under gradually increasing temperature conditions, a crystalline polyester resin with optimized crystallinity can be prepared while minimizing melting between polyester resins during the crystallization process.

[0088] According to the present invention, step (2) may specifically include (2-1) subjecting the polyester resin of step (1) to a first crystallization at 105° C. to 135° C. (specifically, 108° C. to 133° C. or 110° C. to 130° C.); (2-2) subjecting the polyester resin crystallized in step (2-1) to a second crystallization at 120° C. to 175° C. (specifically, 120° C. to 170° C. or 125° C. to 155° C.); and (2-3) subjecting the polyester resin crystallized in step (2-2) to a third crystallization at 140° C. to 180° C. (specifically, 145° C. to 180° C. or 150° C. to 180° C.). Since crystallization is performed in three stages and each crystallization temperature is controlled within the above-mentioned specific range, crystals are uniformly formed inside and outside the polyester resin, and melting between the polyester resins due to surface melting during crystallization can be minimized. Therefore, a polyester resin having optimized crystallinity can be efficiently prepared (with improved productivity), thereby providing a crystalline polyester resin having excellent moldability and recyclability.

[0089] Herein, the first crystallization temperature, the second crystallization temperature, and the third crystallization temperature may be different from each other.

[0090] The crystallization may be carried out under normal pressure or reduced pressure. In order to improve the fluidity of the polyester resin (polyester resin particles), a known fluidizing agent may be added during the crystallization step.

[0091] The crystalline polyester resin prepared by crystallization in the above step (2) may be further subjected to a known solid-state polymerization procedure to control viscosity and molecular weight as required.

[0092] Products

[0093] 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 can be an injection molded article prepared by injection molding.

[0094] Since the product is made of the above crystalline polyester resin, it can have excellent quality (such as heat resistance, mechanical strength, appearance, etc.). In addition, since the product is made of the above crystalline polyester resin, when a recycling process is performed after use, the efficiency of the recycling process can also be excellent.

[0095] The article is not particularly limited, but may be a film; a sheet; or a small or large container (for example, a container for cosmetics, food, etc.).

[0096] Invention Mode

[0097] The present invention will be described in more detail below with reference to embodiments. However, these embodiments are provided only for illustrative purposes, and the present invention is not limited thereto.

[0098] [Example 1]

[0099] Step (1): Preparation of polyester resin

[0100] In a reactor equipped with a column and a condenser (which can be cooled with water), recovered 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 toner (0.005 kg) were charged. Next, after the temperature of the reactor was raised to 265°C, the reaction mixture was stirred at 265°C and 2 kgf / cm 2 The esterification reaction (ES) was carried out under pressure to obtain a transparent reactant.

[0101] Subsequently, the reactant is transferred to a polycondensation reactor, and then a polycondensation reaction (PA) is performed at 270° C. while the pressure of the polycondensation reactor is maintained at a pressure lower than normal pressure. When the intrinsic viscosity (melt intrinsic viscosity) (IV) of the reactant in the polycondensation reactor reaches 0.60 dl / g, the reactant is discharged to the outside of the polycondensation reactor to form a strand. Then, it is solidified with a cooling liquid, and then pelletized so that the average weight of 100 pellets is about 1.0 g to 2.5 g, thereby obtaining polyester resin pellets.

[0102] Then, the obtained polyester resin particles were dried at 50° C. for 10 hours and then crystallized.

[0103] Step (2): Crystallization of polyester resin

[0104] The dried polyester resin pellets were fed into a crystallization reactor at a rate of 1 ton per hour (feed rate: 1 ton / hour), and crystallized three times while increasing the temperature according to the moving position of the polyester resin pellets, thereby obtaining a crystalline polyester resin. In this case, the first crystallization of the polyester resin pellets was performed at 110° C., the second crystallization of the first crystalline polyester resin pellets was performed at 130° C., and the third crystallization of the second crystalline polyester resin pellets was performed at 165° C.

[0105] [Example 2]

[0106] Step (1): Preparation of polyester resin

[0107] In a reactor equipped with a column and a condenser (which can be cooled with water), recovered 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 toner (0.01 kg) were charged. Next, after the temperature of the reactor was raised to 255°C, the reaction mixture was heated to 100 °C at 255°C and 1 kgf / cm 2 The esterification reaction (ES) was carried out under pressure to obtain a transparent reactant.

[0108] Subsequently, the reactant is transferred to a polycondensation reactor, and then a polycondensation reaction (PA) is performed at 285° C. while the pressure of the polycondensation reactor is maintained at a pressure lower than normal pressure. When the intrinsic viscosity (melt intrinsic viscosity) (IV) of the reactant in the polycondensation reactor reaches 0.50 dl / g, the reactant is discharged to the outside of the polycondensation reactor to form a strand. Then, it is solidified with a cooling liquid and then pelletized so that the average weight of 100 pellets is about 1.0 g to 2.5 g, thereby obtaining polyester resin pellets.

[0109] Step (2): Crystallization of polyester resin

[0110] The polyester resin pellets (undried) were fed into a crystallization reactor at a rate of 1 ton per hour (feed rate: 1 ton / hour), and crystallized 3 times while increasing the temperature according to the moving position of the polyester resin pellets, thereby obtaining a crystalline polyester resin. In this case, the first crystallization of the polyester resin pellets was performed at 115° C., the second crystallization of the first crystalline polyester resin pellets was performed at 120° C., and the third crystallization of the second crystalline polyester resin pellets was performed at 160° C.

[0111] [Example 3]

[0112] Step (1): Preparation of polyester resin

[0113] In a reactor equipped with a column and a condenser (which can be cooled with water), recovered 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) were charged. Next, after the temperature of the reactor was raised to 260°C, the reaction mixture was heated at 260°C and 1 kgf / cm 2The esterification reaction (ES) was carried out under pressure to obtain a transparent reactant.

[0114] Subsequently, the reactant was transferred to a polycondensation reactor, and then a polycondensation reaction (PA) was performed at 275° C. while the pressure of the polycondensation reactor was maintained at a pressure lower than normal pressure. When the intrinsic viscosity (melt intrinsic viscosity) (IV) of the reactant in the polycondensation reactor reached 0.78 dl / g, the reactant was discharged to the outside of the polycondensation reactor to form a strand. Then, it was solidified with a cooling liquid and then pelletized so that the average weight of 100 pellets was about 1.0 g to 2.5 g, thereby obtaining polyester resin pellets.

[0115] Then, the obtained polyester resin particles were dried at 40° C. for 9 hours and then crystallized.

[0116] Step (2): Crystallization of polyester resin

[0117] The dried polyester resin pellets were fed into a crystallization reactor at a rate of 1 ton per hour (feed rate: 1 ton / hour), and crystallized 3 times while increasing the temperature according to the moving position of the polyester resin pellets, thereby obtaining a crystallized polyester resin. In this case, the first crystallization of the polyester resin pellets was performed at 120° C., the second crystallization of the first crystallized polyester resin pellets was performed at 135° C., and the third crystallization of the second crystallized polyester resin pellets was performed at 150° C.

[0118] [Example 4]

[0119] Step (1): Preparation of polyester resin

[0120] In a reactor equipped with a column and a condenser (which can be cooled with water), recovered 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 (0.4 kg), blue toner (0.03 kg) and red toner toner (0.01 kg) were charged. Next, after the temperature of the reactor was raised to 250°C, the reaction mixture was heated to 100 °C and heated to 100 °C. The reaction mixture was heated to 200 °C and 100 °C. The reaction mixture was heated to 100 °C and 200 °C. The reaction mixture was heated to 100 °C and 200 °C. 2 The esterification reaction (ES) was carried out under pressure to obtain a transparent reactant.

[0121] Subsequently, the reactant is transferred to a polycondensation reactor, and then a polycondensation reaction (PA) is performed at 285° C. while the pressure of the polycondensation reactor is maintained at a pressure lower than normal pressure. When the intrinsic viscosity (melt intrinsic viscosity) (IV) of the reactant in the polycondensation reactor reaches 0.85 dl / g, the reactant is discharged to the outside of the polycondensation reactor to form a strand. Then, it is solidified with a cooling liquid and then pelletized so that the average weight of 100 pellets is about 1.0 g to 2.5 g, thereby obtaining polyester resin pellets.

[0122] Step (2): Crystallization of polyester resin

[0123] The polyester resin pellets (undried) were fed into a crystallization reactor at a rate of 1 ton per hour (feed rate: 1 ton / hour), and crystallized 3 times while increasing the temperature according to the moving position of the polyester resin pellets, thereby obtaining a crystalline polyester resin. In this case, the first crystallization of the polyester resin pellets was performed at 110° C., the second crystallization of the first crystalline polyester resin pellets was performed at 170° C., and the third crystallization of the second crystalline polyester resin pellets was performed at 180° C.

[0124] [Example 5]

[0125] Step (1): Preparation of polyester resin

[0126] Polyester resin particles were obtained by the same procedure as in Example 1. Then, the obtained polyester resin particles were dried at 55° C. for 4 hours and then crystallized.

[0127] Step (2): Crystallization of polyester resin

[0128] The dried polyester resin pellets were fed into a crystallization reactor at a rate of 1 ton per hour (feed rate: 1 ton / hour), and crystallized 3 times while increasing the temperature according to the moving position of the polyester resin pellets, thereby obtaining a crystallized polyester resin. In this case, the first crystallization of the polyester resin pellets was performed at 125° C., the second crystallization of the first crystallized polyester resin pellets was performed at 130° C., and the third crystallization of the second crystallized polyester resin pellets was performed at 140° C.

[0129] [Example 6]

[0130] Step (1): Preparation of polyester resin

[0131] By the same procedure as in Example 3, polyester resin particles were obtained.

[0132] Step (2): Crystallization of polyester resin

[0133] The polyester resin pellets (undried) were fed into a crystallization reactor at a rate of 1 ton per hour (feed rate: 1 ton / hour), and crystallized 3 times while increasing the temperature according to the moving position of the polyester resin pellets, thereby obtaining a crystallized polyester resin. In this case, the first crystallization of the polyester resin pellets was performed at 130° C., the second crystallization of the first crystallized polyester resin pellets was performed at 150° C., and the third crystallization of the second crystallized polyester resin pellets was performed at 180° C.

[0134] [Comparative Example 1]

[0135] Step (1): Preparation of polyester resin

[0136] By the same procedure as in Example 3, polyester resin particles were obtained.

[0137] Step (2): Crystallization of polyester resin

[0138] The polyester resin pellets (not dried) were fed into a crystallization reactor at a rate of 1 ton per hour (feed rate: 1 ton / hour), and crystallization was performed 3 times while the temperature was lowered according to the moving position of the polyester resin pellets, thereby obtaining a crystallized polyester resin. In this case, the first crystallization of the polyester resin pellets was performed at 160° C., the second crystallization of the first crystallized polyester resin pellets was performed at 140° C., and the third crystallization of the second crystallized polyester resin pellets was performed at 120° C.

[0139] [Comparative Example 2]

[0140] Step (1): Preparation of polyester resin

[0141] Polyester resin particles were obtained by the same procedure as in Example 3. Then, the obtained polyester resin particles were dried at 55° C. for 3 hours and then crystallized.

[0142] Step (2): Crystallization of polyester resin

[0143] The dried polyester resin pellets were fed into a crystallization reactor at a rate of 1 ton per hour (feed rate: 1 ton / hour), and crystallized 3 times while increasing the temperature according to the moving position of the polyester resin pellets, thereby obtaining a crystallized polyester resin. In this case, the first crystallization of the polyester resin pellets was performed at 140° C., the second crystallization of the first crystallized polyester resin pellets was performed at 160° C., and the third crystallization of the second crystallized polyester resin pellets was performed at 200° C.

[0144] [Comparative Example 3]

[0145] Step (1): Preparation of polyester resin

[0146] By the same procedure as in Example 4, polyester resin particles were obtained.

[0147] Step (2): Crystallization of polyester resin

[0148] The polyester resin pellets (not dried) were fed into a crystallization reactor at a rate of 1 ton per hour (feed rate: 1 ton / hour), and a crystallization process was performed while increasing the temperature according to the moving position of the polyester resin pellets, thereby obtaining a crystalline polyester resin. In this case, the first crystallization of the polyester resin pellets was performed at 100° C., the second crystallization of the first crystalline polyester resin pellets was performed at 160° C., and the third crystallization of the second crystalline polyester resin pellets was performed at 190° C.

[0149] [Comparative Example 4]

[0150] Step (1): Preparation of polyester resin

[0151] By the same procedure as in Example 1, polyester resin particles were obtained.

[0152] Step (2): Crystallization of polyester resin

[0153] The polyester resin pellets (undried) were fed into a crystallization reactor at a rate of 1 ton per hour (feed rate: 1 ton / hour) and subjected to a primary crystallization process at 170° C., thereby obtaining a crystalline polyester resin.

[0154] [Comparative Example 5]

[0155] Step (1): Preparation of polyester resin

[0156] Polyester resin particles were obtained by the same procedure as in Example 3. Then, the obtained polyester resin particles were dried at 40° C. for 3 hours and then crystallized.

[0157] Step (2): Crystallization of polyester resin

[0158] The dried polyester resin pellets were fed into a crystallization reactor at a rate of 1 ton per hour (feed rate: 1 ton / hour), and two crystallization processes were performed while increasing the temperature according to the moving position of the polyester resin pellets, thereby obtaining a crystallized polyester resin. In this case, the first crystallization of the polyester resin pellets was performed at 70° C., and the second crystallization of the first crystallized polyester resin pellets was performed at 160° C.

[0159] [Test Example 1]

[0160] The crystalline polyester resins prepared in Examples 1 to 6 and Comparative Examples 1 to 5 were each analyzed by differential scanning calorimetry (DSC) to determine whether a melting temperature (T m ). The results are shown in the following Tables 1 and 2. DSC analysis was performed as follows.

[0161] DSC analysis apparatus: Mettler Toledo DSC 1 model was used.

[0162] Sample preparation: About 6 to 10 mg of each crystalline polyester resin was taken and filled into an aluminum pan.

[0163] Scanning conditions: heating from room temperature to 280°C at a rate of 10°C / min, followed by annealing at 280°C for 3 minutes to obtain the DSC curve.

[0164] Melting temperature (T m ) confirmation: The temperature at which the endothermic peak appears during the temperature rise in the obtained DSC curve is defined as the melting temperature. Then, the melting temperature (T m ) Calculate the heat of fusion (ΔH) and X / Y ratio (rounded to the second decimal place).

[0165] [Test Example 2]

[0166] The weight (kg) of the molten material produced per ton in the total output (kg / hour) was measured, and then the melting rate was calculated according to the following Relationship 2. The results are shown in Tables 1 and 2 below.

[0167] [Equation 2]

[0168] Melting rate (%) = (W F / W T )×100

[0169] In equation 2, W T is the total weight (total output) of the crystalline polyester resin produced per unit time (1 hour), and W F It is the weight of the melt produced per ton of the crystalline polyester resin produced (the total production is obtained by dividing each portion into 1 ton, dividing into crystalline polyester resin samples, and measuring the weight of the molten material contained in the samples).

[0170] The molten material (polyester resin molten material) is a material that cannot pass through a vibrator having a mesh opening of 12.5 mm.

[0171] [Test Example 3]

[0172] The crystalline polyester resins prepared in Examples 1 to 6 and Comparative Examples 1 to 5 were respectively injection molded at a temperature of 250 to 260° C. using an ENGEL 25 device to prepare injection molded samples with a length of 100 mm, a width of 100 mm, and a thickness of 3 mm, and their plasticity was evaluated according to the following criteria. The results are shown in the following Tables 1 and 2.

[0173] ◎: The injection molded specimen has no fisheyes and no unmelted (the state where the resin particles are not melted), and continuous injection molding can be performed

[0174] ○: There is no unmelted part and one or less fisheyes in the injection molded sample, and the continuous injection process can be performed

[0175] △: There are two or more unmelted and fish eyes in the injection sample, and continuous injection process can be carried out at the same time

[0176] ×: Melting occurs between resin particles, and continuous injection process is impossible

[0177] [Table 1]

[0178]

[0179] [Table 2]

[0180]

[0181] Referring to Table 1 above, the crystalline polyester resins according to Examples 1 to 6 of the present invention have a very low melting rate of 5% or less during crystallization and an X / Y ratio controlled within the range of the present invention, thereby having excellent productivity and plasticity and optimized crystallinity.

[0182] In contrast, referring to Table 2 above, in the crystalline polyester resin of Comparative Example 1, in which crystallization occurs under conditions of gradual temperature reduction, and in the crystalline polyester resins of Comparative Examples 2 and 3, in which the crystallization temperature is outside the range of the present invention, the melting rate exceeds 5%, resulting in poor productivity of the crystalline polyester resin. In addition, it was confirmed that in Comparative Examples 1 to 3, fish eyes and non-melting were formed during injection molding due to excessive crystallization, resulting in poor plasticity. In addition, in the crystalline polyester resin of Comparative Example 4, in which crystallization was performed once at a low temperature, and in the crystalline polyester resin of Comparative Example 5, in which crystallization was performed twice (translucency was shown due to insufficient crystallization), the melting rate was very high during the crystallization process, and crystallization was impossible or insufficient. In addition, in Comparative Example 5, melting occurred between the crystalline polyester resins, resulting in poor plasticity.

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 when the crystalline polyester resin is analyzed by differential scanning calorimetry (DSC), when the temperature is raised to 280°C at a scanning rate of 10°C / min, two or more melting temperatures (T m ), and satisfy the following relationship 1: [Equation 1] 4 <X / Y<70 In Relational Formula 1, X is the sum of the heat of fusion (ΔH) occurring at a melting temperature of 200°C or higher, and Y is the sum of the heat of fusion (ΔH) occurring at a melting temperature of less than 200°C.

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

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

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

5. The crystalline polyester resin according to claim 1, wherein The sum (Y) of the heat of fusion (ΔH) at the melting temperature occurring below 200° C. is 0.1 J / g 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-naphthalene dicarboxylic acid, dimethyl 2,6-naphthalene dicarboxylate, diphthalic acid, 1,4-cyclohexane dicarboxylic acid, dimethyl 1,3-cyclohexane dicarboxylate, 1,4-cyclohexane dicarboxylic acid, dimethyl 1,3-cyclohexane dicarboxylate, 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. The crystalline polyester resin according to 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, 1,4-cyclohexanedicarboxylic acid dimethyl ester, 1,3-cyclohexanedicarboxylic acid dimethyl ester, recycled isophthalic acid, recycled phthalic acid, or a combination thereof.

8. The crystalline polyester resin according to claim 7, wherein The second dicarboxylic acid component is used in an amount of 5 mol% or less based on the total mol% of the dicarboxylic acid components.

9. The crystalline polyester resin according to claim 1, wherein The diol component comprises a diol selected from the group consisting of bis-2-hydroxyethyl terephthalate, isosorbide, neopentyl glycol, ethylene glycol, diethylene glycol, cyclohexanedimethanol, 1,2-propylene glycol, 1,3-propylene glycol, 2-methyl-1,3-propylene glycol, 2-methylene-1,3-propylene glycol, 2-ethyl-1,3-propylene glycol, 2-isopropyl-1,3-propylene glycol, 2,2-dimethyl-1,3-propylene glycol, 1,4-butylene glycol, 2,3-butylene glycol, 3-methyl-1,5-pentanediol, 3-methyl -2,4-pentanediol, 1,6-hexanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 4-(hydroxymethyl)cyclohexylmethyl-4-(hydroxymethyl)cyclohexanecarboxylate, 4-(4-(hydroxymethyl)cyclohexylmethoxymethyl)cyclohexanemethanol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, at least one of the group consisting of recovered bis-2-hydroxyethyl terephthalate, recovered isosorbide, recovered neopentyl glycol, recovered ethylene glycol, recovered diethylene glycol, and recovered cyclohexanedimethanol.

10. The crystalline polyester resin according to 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, recycled isosorbide, recycled neopentyl glycol, recycled diethylene glycol, recycled cyclohexanedimethanol, or a combination thereof.

11. The crystalline polyester resin according to claim 10, wherein The third diol component is used in an amount of 20 mol% or less based on the total mol% of the diol components.

12. The crystalline polyester resin according to claim 1, wherein The melting rate is 5% or less according to the following relationship 2: [Equation 2] Melting rate (%) = (W F / W T )×100 In equation 2, W T is the total weight of the crystalline polyester resin produced per unit time (1 hour), and W F It is the weight of molten material produced per ton of crystalline polyester resin produced, wherein the molten material is material that cannot pass through a vibrator having a mesh opening of 12.5 mm. 13 . The crystalline polyester resin according to claim 1 , further comprising a repeating unit derived from a branching agent having 3 or more functional groups.

14. The crystalline polyester resin according to claim 13, wherein The content of the repeating unit derived from the branching agent is 0.001 wt % to 15 wt % based on the total weight percentage of the diol repeating unit. 15 . The crystalline polyester resin according to claim 1 , having an intrinsic viscosity (IV) of 0.5 to 1.3 dl / g.

16. A method for preparing a crystalline polyester resin, comprising: (1) polymerizing a diol component and a dicarboxylic acid component to prepare a polyester resin; (2) crystallizing the polyester resin one or more times, wherein when the crystalline polyester resin is analyzed by differential scanning calorimetry (DSC), two or more melting temperatures (T m ), and satisfy the following relationship 1: [Equation 1] 4 <X / Y<70 In Relational Formula 1, X is the sum of the heat of fusion (ΔH) occurring at a melting temperature of 200°C or higher, and Y is the sum of the heat of fusion (ΔH) occurring at a melting temperature of less than 200°C.

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 ranging from 105°C to 185°C.

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

19. The method for preparing a crystalline polyester resin according to claim 16, wherein: Step (2) comprises: (2-1) subjecting the polyester resin of step (1) to a first crystallization at 105° C. to 135° C.; (2-2) subjecting the polyester resin crystallized in step (2-1) to a second crystallization at 120° C. to 175° C.; and (2-3) The polyester resin crystallized in step (2-2) is crystallized for the third time at 140°C to 180°C. 20 . The method for producing a crystalline polyester resin according to claim 16 , further comprising drying the polyester resin obtained in step (1) before performing step (2).

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

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

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