POLYESTER COPOLYMER COMPRISING RECYCLED MONOMERS

Abstract

In the present disclosure, it is possible to identify and select recycled bis-2-hydroxyethyl terephthalate of a certain quality or higher, and thus the quality of a polyester resin prepared using the recycled bis-2-hydroxyethyl terephthalate can be improved.

Claims

1. A polyester resin obtained by copolymerizing recycled bis-2-hydroxyethyl terephthalate, a dicarboxylic acid or its derivative, and a diol containing ethylene glycol and a comonomer and having a structure in which a moiety derived from the bis-2-hydroxyethyl terephthalate, an acid moiety derived from the dicarboxylic acid or its derivative, and a diol moiety derived from the diol are repeated, wherein the polyester resin satisfies the following Equation 1:
0<(AB/100)<10[Equation 1] in Equation 1, A is a YID value of a 25 wt % recycled bis-2-hydroxyethyl terephthalate solution, and B is wt % of a moiety derived from recycled bis-2-hydroxyethyl terephthalate based on a total weight of the polyester copolymer.

2. The polyester resin of claim 1, wherein a solvent of the 25 wt % recycled bis-2-hydroxyethyl terephthalate solution in A is dimethylformaldehyde, ethylene glycol, water, or cyclohexanedimethanol.

3. The polyester resin of claim 1, wherein A is more than 0 and less than 15.

4. The polyester resin of claim 1, wherein B is 1 to 95.

5. The polyester resin of claim 1, wherein the dicarboxylic acid or its derivative is terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyl dicarboxylic acid, 4,4-stilbenedicarboxylic acid, 2,5-furandicarboxylic acid, or 2,5-thiophenedicarboxylic acid.

6. The polyester resin of claim 1, wherein the comonomer is cyclohexanedimethanol, isosorbide, or diethylene glycol.

7. The polyester resin of claim 1, wherein the polyester copolymer has an intrinsic viscosity of 0.50 to 1.0 dl/g.

8. The polyester resin of claim 1, wherein a value of (Hunter L value)(Hunter b value) measured with respect to a 6 mm-thick specimen of the polyester copolymer is 83 or more.

9. A product comprising the polyester copolymer according claim 1.

10. A product comprising the polyester copolymer according claim 2.

11. A product comprising the polyester copolymer according claim 3.

12. A product comprising the polyester copolymer according claim 4.

13. A product comprising the polyester copolymer according claim 5.

14. A product comprising the polyester copolymer according claim 6.

15. A product comprising the polyester copolymer according claim 7.

16. A product comprising the polyester copolymer according claim 8.

17. A product comprising the polyester copolymer according claim 9.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0044] Hereinafter, preferred examples are presented to help the understanding of the present invention. However, the following examples are provided only for easier understanding of the present invention, and the present invention is not limited thereto.

[0045] In the following Examples and Comparative Examples, physical properties were evaluated as follows.

[0046] (1) Residue Composition

[0047] The residue composition (mol %) derived from acid and diol in the polyester resin was confirmed through 1H-NMR spectrum obtained at 25 C. using a nuclear magnetic resonance apparatus (JEOL, 600 MHz FT-NMR) after dissolving the sample in a CDCl.sub.3 solvent at a concentration of 3 mg/mL. In addition, the residue of TMA was confirmed by quantitative analysis of spectrum in which the content of benzene-1,2,4-triethylcarboxylate produced by the reaction of ethanol with TMA through ethanolysis was measured at 250 C. using gas chromatography (Agilent Technologies, 7890B). And, it was confirmed as the content (wt %) based on a total weight of the polyester resin.

[0048] (2) Intrinsic Viscosity

[0049] After dissolving the polyester copolymer in orthochlorophenol (OCP) at a concentration of 0.12% at 150 C., the intrinsic viscosity was measured in a constant temperature bath at 35 C. using an Ubbelohde viscometer. Specifically, a temperature of the viscometer was maintained at 35 C., and the time taken (efflux time; t.sub.0) for a solvent to pass between certain internal sections of the viscometer and the time taken (t) for a solution to pass the viscometer were measured. Subsequently, a specific viscosity was calculated by substituting to and t into Formula 1, and the intrinsic viscosity was calculated by substituting the calculated specific viscosity into Formula 2.

[00001]$\begin{array}{cc}{}_{\mathrm{sp}}=\frac{t-t_0}{t_0}& \left[\mathrm{Formula}1\right]\end{array}$$\begin{array}{cc}\left[\right]=\frac{\sqrt{1+4A{}_{\mathrm{sp}}}-1}{2\mathrm{Ac}}& \left[\mathrm{Formula}2\right]\end{array}$

[0050] (3) Plaque Color L-b

[0051] The chromaticity and brightness of the sample were measured using Varian Cary 5 UV/Vis/NIR spectrophotometer equipped with a diffuse reflection accessory. A polyester resin specimen having a thickness of 6 mm was prepared, and transmission data was obtained with Illuminant D65 at an observer angle of 2. This was processed using a color analysis device in the Grams/32 software to calculate Hunter L*a*b* values, and the results (L-b) by subtracting the b value from the L value were described in the table below.

[0052] (4) YID

[0053] Transmission data was obtained with Illuminant D65 at an observer angle of 2 with respect to the BHET solution, and measured using a CIE colorimeter. This was processed using a color analysis device in the software to calculate Hunter L*a*b*YID values, and the YID values are described in the table below.

Example 1

[0054] Bis-2-hydroxyethyl terephthalate (BHET) with commercially available quality was used, and the following experiments were performed by selecting 8 random (#1 to #8) BHETs.

[0055] (1) YID Measurement of BHET Solution

[0056] A solution was prepared by dissolving one of 8 types of BHETs in DMF (dimethylformamide) to 25 wt % at room temperature (23 C.). YID was measured for each solution, and the results are shown in Table 1 below.

[0057] (2) Preparation of Polyester Copolymer

[0058] The following polyester copolymer was prepared with each BHET.

[0059] r-BHET (3461.1 g), TPA (969.4 g), EG (12.1 g), CHDM (140.2 g), and ISB (113.7 g) were placed in a 10 L reactor to which a column, and a condenser capable of being cooled by water were connected, and GeO.sub.2 (1.0 g) as a catalyst, phosphoric acid (1.46 g) as a stabilizer, and cobalt acetate (0.7 g) as a coloring agent were added thereto.

[0060] Then, nitrogen was injected into the reactor to form a pressurized state in which the pressure of the reactor was higher than normal pressure by 1.0 kgf/cm.sup.2 (absolute pressure: 1495.6 mmHg). Then, the temperature of the reactor was raised to 220 C. over 90 minutes, maintained at 220 C. for 2 hours, and then raised to 260 C. over 2 hours. Thereafter, an esterification reaction proceeded until the mixture in the reactor became transparent with the naked eye while maintaining the temperature of the reactor at 260 C. In this process, by-products flowed through the column and condenser. When the esterification reaction was completed, the nitrogen in the pressurized reactor was discharged to the outside to lower the pressure of the reactor to normal pressure, and then the mixture in the reactor was transferred to a 7 L reactor capable of vacuum reaction.

[0061] Then, the pressure of the reactor was reduced from normal pressure to 5 Torr (absolute pressure: 5 mmHg) over 30 minutes, and the temperature of the reactor was raised to 280 C. over 1 hour to proceed a polycondensation reaction while maintaining the pressure of the reactor at 1 Torr (absolute pressure: 1 mmHg) or less. In the initial stage of the polycondensation reaction, a stirring rate was set high, but when the stirring force is weakened due to an increase in the viscosity of the reactant as the polycondensation reaction progresses or the temperature of the reactant rises above the set temperature, the stirring rate may be appropriately adjusted. The polycondensation reaction was performed until an intrinsic viscosity (IV) of the mixture (melt) in the reactor became 0.60 dl/g. When the intrinsic viscosity of the mixture in the reactor reached a desired level, the mixture was discharged out of the reactor and stranded. This was solidified with a cooling liquid and granulated to have an average weight of about 12 to 14 mg.

[0062] The particles were allowed to stand at 150 C. for 1 hour to crystallize, and then put into a 20 L solid-phase polymerization reactor. Then, nitrogen was flowed into the reactor at a rate of 50 L/min. Herein, the temperature of the reactor was raised from room temperature to 140 C. at a rate of 40 C./hour, and maintained at 140 C. C. for 3 hours. Thereafter, the temperature was further raised to 200 C. at a rate of 40 C./hour, and maintained at 200 C. The solid-phase polymerization reaction was performed until the intrinsic viscosity (IV) of the particles in the reactor reached 0.95 dl/g to prepare a polyester copolymer.

TABLE-US-00001 TABLE 1 YID of BHET solution BHET content (wt %) Yellow Factor.sup.1) #1 5.9 30 1.8 #2 14.4 30 4.3 #3 34.0 30 10.2 #4 42.1 30 12.6 #5 14.0 30 4.2 #6 11.1 30 3.3 #7 1.8 30 0.5 #8 4.3 30 1.3 .sup.1)(YID of BHET solution) * (BHET content)/100

[0063] As shown in Table 1, when the BHET YID was greater than 15 (#3 and #4), the Yellow Factor also exceeded 10. From this, when the BHET YID value is 15 or less, the color quality of the polyester copolymer is expected to be excellent. Hereinafter, this was confirmed in detail in the remaining examples.

Example 2

[0064] A solution was prepared by dissolving BHET used in one of the following Examples and Comparative Examples in DMF to 25 wt %, and YID of each solution was measured and shown in Table 2 below.

Example 2-1

[0065] BHET (1269.7 g), TPA (terephthalic acid; 2361.8 g), EG (ethylene glycol; 673.5 g), CHDM (1,4-cyclohexanedimethanol; 221.5 g), and ISB (isosorbide; 98.2 g) were placed in a 10 L reactor to which a column, and a condenser capable of being cooled by water were connected, and GeO.sub.2 (1.0 g) as a catalyst, phosphoric acid (1.46 g) as a stabilizer, and cobalt acetate (0.7 g) as a coloring agent were added thereto.

[0066] Then, nitrogen was injected into the reactor to form a pressurized state in which the pressure of the reactor was higher than normal pressure by 1.0 kgf/cm.sup.2 (absolute pressure: 1495.6 mmHg). Then, the temperature of the reactor was raised to 220 C. over 90 minutes, maintained at 220 C. for 2 hours, and then raised to 260 C. over 2 hours. Thereafter, an esterification reaction proceeded until the mixture in the reactor became transparent with the naked eye while maintaining the temperature of the reactor at 260 C. In this process, by-products flowed through the column and condenser. When the esterification reaction was completed, the nitrogen in the pressurized reactor was discharged to the outside to lower the pressure of the reactor to normal pressure, and then the mixture in the reactor was transferred to a 7 L reactor capable of vacuum reaction.

[0067] Then, the pressure of the reactor was reduced from normal pressure to 5 Torr (absolute pressure: 5 mmHg) over 30 minutes, and the temperature of the reactor was raised to 280 C. over 1 hour to proceed a polycondensation reaction while maintaining the pressure of the reactor at 1 Torr (absolute pressure: 1 mmHg) or less. In the initial stage of the polycondensation reaction, a stirring rate was set high, but when the stirring force is weakened due to an increase in the viscosity of the reactant as the polycondensation reaction progresses or the temperature of the reactant rises above the set temperature, the stirring rate may be appropriately adjusted. The polycondensation reaction was performed until an intrinsic viscosity (IV) of the mixture (melt) in the reactor became 0.55 dl/g. When the intrinsic viscosity of the mixture in the reactor reached a desired level, the mixture was discharged out of the reactor and stranded. This was solidified with a cooling liquid and granulated to have an average weight of about 12 to 14 mg.

[0068] The particles were allowed to stand at 150 C. for 1 hour to crystallize, and then put into a 20 L solid-phase polymerization reactor. Then, nitrogen was flowed into the reactor at a rate of 50 L/min. Herein, the temperature of the reactor was raised from room temperature to 140 C. at a rate of 40 C./hour, and maintained at 140 C. for 3 hours. Thereafter, the temperature was further raised to 200 C. at a rate of 40 C./hour, and maintained at 200 C. The solid-phase polymerization reaction was performed until the intrinsic viscosity (IV) of the particles in the reactor reached 0.70 dl/g to prepare a polyester copolymer.

Example 2-2

[0069] r-BHET (3461.1 g), TPA (969.4 g), EG (12.1 g), CHDM (140.2 g), and ISB (113.7 g) were placed in a 10 L reactor to which a column, and a condenser capable of being cooled by water were connected, and GeO.sub.2 (1.0 g) as a catalyst, phosphoric acid (1.46 g) as a stabilizer, and cobalt acetate (0.7 g) as a coloring agent were added thereto.

[0070] Then, nitrogen was injected into the reactor to form a pressurized state in which the pressure of the reactor was higher than normal pressure by 1.0 kgf/cm.sup.2 (absolute pressure: 1495.6 mmHg). Then, the temperature of the reactor was raised to 220 C. over 90 minutes, maintained at 220 C. for 2 hours, and then raised to 260 C. over 2 hours. Thereafter, an esterification reaction proceeded until the mixture in the reactor became transparent with the naked eye while maintaining the temperature of the reactor at 260 C. In this process, by-products flowed through the column and condenser. When the esterification reaction was completed, the nitrogen in the pressurized reactor was discharged to the outside to lower the pressure of the reactor to normal pressure, and then the mixture in the reactor was transferred to a 7 L reactor capable of vacuum reaction.

[0071] Then, the pressure of the reactor was reduced from normal pressure to 5 Torr (absolute pressure: 5 mmHg) over 30 minutes, and the temperature of the reactor was raised to 280 C. over 1 hour to proceed a polycondensation reaction while maintaining the pressure of the reactor at 1 Torr (absolute pressure: 1 mmHg) or less. In the initial stage of the polycondensation reaction, a stirring rate was set high, but when the stirring force is weakened due to an increase in the viscosity of the reactant as the polycondensation reaction progresses or the temperature of the reactant rises above the set temperature, the stirring rate may be appropriately adjusted. The polycondensation reaction was performed until an intrinsic viscosity (IV) of the mixture (melt) in the reactor became 0.60 dl/g. When the intrinsic viscosity of the mixture in the reactor reached a desired level, the mixture was discharged out of the reactor and stranded. This was solidified with a cooling liquid and granulated to have an average weight of about 12 to 14 mg.

[0072] The particles were allowed to stand at 150 C. for 1 hour to crystallize, and then put into a 20 L solid-phase polymerization reactor. Then, nitrogen was flowed into the reactor at a rate of 50 L/min. Herein, the temperature of the reactor was raised from room temperature to 140 C. at a rate of 40 C./hour, and maintained at 140 C. for 3 hours. Thereafter, the temperature was further raised to 200 C. at a rate of 40 C./hour, and maintained at 200 C. The solid-phase polymerization reaction was performed until the intrinsic viscosity (IV) of the particles in the reactor reached 0.95 dl/g to prepare a polyester copolymer.

Example 2-3

[0073] r-BHET (4983.7 g), TPA (245.2 g), and CHDM (121.5 g) were placed in a 10 L reactor to which a column, and a condenser capable of being cooled by water were connected, and TiO.sub.2/SiO.sub.2 copolymer (0.5 g) as a catalyst, phosphoric acid (1.46 g) as a stabilizer, Polysynthren Blue RLS (manufactured by Clarient, 0.016 g) as a blue toner, and Solvaperm Red BB (manufactured by Clarient, 0.004 g) as a red toner were added thereto.

[0074] Then, nitrogen was injected into the reactor to form a pressurized state in which the pressure of the reactor was higher than normal pressure by 0.5 kgf/cm.sup.2 (absolute pressure: 1127.8 mmHg). Then, the temperature of the reactor was raised to 220 C. over 90 minutes, maintained at 220 C. for 2 hours, and then raised to 260 C. over 2 hours. Thereafter, an esterification reaction proceeded until the mixture in the reactor became transparent with the naked eye while maintaining the temperature of the reactor at 260 C. In this process, by-products flowed through the column and condenser. When the esterification reaction was completed, the nitrogen in the pressurized reactor was discharged to the outside to lower the pressure of the reactor to normal pressure, and then the mixture in the reactor was transferred to a 7 L reactor capable of vacuum reaction.

[0075] Then, the pressure of the reactor was reduced from normal pressure to 5 Torr (absolute pressure: 5 mmHg) over 30 minutes, and the temperature of the reactor was raised to 275 C. over 1 hour to proceed a polycondensation reaction while maintaining the pressure of the reactor at 1 Torr (absolute pressure: 1 mmHg) or less. In the initial stage of the polycondensation reaction, a stirring rate was set high, but when the stirring force is weakened due to an increase in the viscosity of the reactant as the polycondensation reaction progresses or the temperature of the reactant rises above the set temperature, the stirring rate may be appropriately adjusted. The polycondensation reaction was performed until an intrinsic viscosity (IV) of the mixture (melt) in the reactor became 0.60 dl/g. When the intrinsic viscosity of the mixture in the reactor reached a desired level, the mixture was discharged out of the reactor and stranded. This was solidified with a cooling liquid and granulated to have an average weight of about 12 to 14 mg.

[0076] The particles were allowed to stand at 150 C. for 1 hour to crystallize, and then put into a 20 L solid-phase polymerization reactor. Then, nitrogen was flowed into the reactor at a rate of 50 L/min. Herein, the temperature of the reactor was raised from room temperature to 140 C. at a rate of 40 C./hour, and maintained at 140 C. for 3 hours. Thereafter, the temperature was further raised to 210 C. at a rate of 40 C./hour, and maintained at 210 C. The solid-phase polymerization reaction was performed until the intrinsic viscosity (IV) of the particles in the reactor reached 0.80 dl/g to prepare a polyester copolymer.

Example 2-4

[0077] r-BHET (795.8 g), TPA (3814.0 g), EG (1554.0 g), and CHDM (188.0 g) were placed in a 10 L reactor to which a column, and a condenser capable of being cooled by water were connected, and TiO.sub.2/SiO.sub.2 copolymer (0.5 g) as a catalyst, phosphoric acid (1.46 g) as a stabilizer, and cobalt acetate (1.1 g) as a coloring agent were added thereto.

[0078] Then, nitrogen was injected into the reactor to form a pressurized state in which the pressure of the reactor was higher than normal pressure by 1.0 kgf/cm.sup.2 (absolute pressure: 1495.6 mmHg). Then, the temperature of the reactor was raised to 220 C. over 90 minutes, maintained at 220 C. for 2 hours, and then raised to 250 C. over 2 hours. Thereafter, an esterification reaction proceeded until the mixture in the reactor became transparent with the naked eye while maintaining the temperature of the reactor at 250 C. In this process, by-products flowed through the column and condenser. When the esterification reaction was completed, the nitrogen in the pressurized reactor was discharged to the outside to lower the pressure of the reactor to normal pressure, and then the mixture in the reactor was transferred to a 7 L reactor capable of vacuum reaction.

[0079] Then, the pressure of the reactor was reduced from normal pressure to 5 Torr (absolute pressure: 5 mmHg) over 30 minutes, and the temperature of the reactor was raised to 265 C. over 1 hour to proceed a polycondensation reaction while maintaining the pressure of the reactor at 1 Torr (absolute pressure: 1 mmHg) or less. In the initial stage of the polycondensation reaction, a stirring rate was set high, but when the stirring force is weakened due to an increase in the viscosity of the reactant as the polycondensation reaction progresses or the temperature of the reactant rises above the set temperature, the stirring rate may be appropriately adjusted. The polycondensation reaction was performed until an intrinsic viscosity (IV) of the mixture (melt) in the reactor became 0.55 dl/g. When the intrinsic viscosity of the mixture in the reactor reached a desired level, the mixture was discharged out of the reactor and stranded. This was solidified with a cooling liquid and granulated to have an average weight of about 12 to 14 mg.

[0080] The particles were allowed to stand at 150 C. for 1 hour to crystallize, and then put into a 20 L solid-phase polymerization reactor. Then, nitrogen was flowed into the reactor at a rate of 50 L/min. Herein, the temperature of the reactor was raised from room temperature to 140 C. at a rate of 40 C./hour, and maintained at 140 C. for 3 hours. Thereafter, the temperature was further raised to 220 C. at a rate of 40 C./hour, and maintained at 220 C. The solid-phase polymerization reaction was performed until the intrinsic viscosity (IV) of the particles in the reactor reached 0.85 dl/g to prepare a polyester copolymer.

Example 2-5

[0081] r-BHET (2439.2 g), TPA (1471.5 g), EG (68.7 g), and CHDM (797.8 g) were placed in a 10 L reactor to which a column, and a condenser capable of being cooled by water were connected, and TiO.sub.2 (1.0 g) as a catalyst, phosphoric acid (1.46 g) as a stabilizer, and cobalt acetate (0.8 g) as a coloring agent were added thereto.

[0082] Then, nitrogen was injected into the reactor to form a pressurized state in which the pressure of the reactor was higher than normal pressure by 2.0 kgf/cm.sup.2 (absolute pressure: 2231.1 mmHg). Then, the temperature of the reactor was raised to 220 C. over 90 minutes, maintained at 220 C. for 2 hours, and then raised to 255 C. over 2 hours. Thereafter, an esterification reaction proceeded until the mixture in the reactor became transparent with the naked eye while maintaining the temperature of the reactor at 255 C. In this process, by-products flowed through the column and condenser. When the esterification reaction was completed, the nitrogen in the pressurized reactor was discharged to the outside to lower the pressure of the reactor to normal pressure, and then the mixture in the reactor was transferred to a 7 L reactor capable of vacuum reaction.

[0083] Then, the pressure of the reactor was reduced from normal pressure to 5 Torr (absolute pressure: 5 mmHg) over 30 minutes, and the temperature of the reactor was raised to 285 C. over 1 hour to proceed a polycondensation reaction while maintaining the pressure of the reactor at 1 Torr (absolute pressure: 1 mmHg) or less. In the initial stage of the polycondensation reaction, a stirring rate was set high, but when the stirring force is weakened due to an increase in the viscosity of the reactant as the polycondensation reaction progresses or the temperature of the reactant rises above the set temperature, the stirring rate may be appropriately adjusted. The polycondensation reaction was performed until an intrinsic viscosity (IV) of the mixture (melt) in the reactor became 0.70 dl/g. When the intrinsic viscosity of the mixture in the reactor reached a desired level, the mixture was discharged out of the reactor and stranded. This was solidified with a cooling liquid and granulated to have an average weight of about 12 to 14 mg to prepare a polyester copolymer.

Example 2-6

[0084] r-BHET (1320.0 g), TPA (2164.2 g), EG (599.2 g), and CHDM (525.1 g) were placed in a 10 L reactor to which a column, and a condenser capable of being cooled by water were connected, and GeO.sub.2 (1.0 g) as a catalyst, phosphoric acid (1.46 g) as a stabilizer, and cobalt acetate (1.0 g) as a coloring agent were added thereto.

[0085] Then, nitrogen was injected into the reactor to form a pressurized state in which the pressure of the reactor was higher than normal pressure by 1.5 kgf/cm.sup.2 (absolute pressure: 1715.5 mmHg). Then, the temperature of the reactor was raised to 220 C. over 90 minutes, maintained at 220 C. for 2 hours, and then raised to 250 C. over 2 hours. Thereafter, an esterification reaction proceeded until the mixture in the reactor became transparent with the naked eye while maintaining the temperature of the reactor at 250 C. In this process, by-products flowed through the column and condenser. When the esterification reaction was completed, the nitrogen in the pressurized reactor was discharged to the outside to lower the pressure of the reactor to normal pressure, and then the mixture in the reactor was transferred to a 7 L reactor capable of vacuum reaction.

[0086] Then, the pressure of the reactor was reduced from normal pressure to 5 Torr (absolute pressure: 5 mmHg) over 30 minutes, and the temperature of the reactor was raised to 270 C. over 1 hour to proceed a polycondensation reaction while maintaining the pressure of the reactor at 1 Torr (absolute pressure: 1 mmHg) or less. In the initial stage of the polycondensation reaction, a stirring rate was set high, but when the stirring force is weakened due to an increase in the viscosity of the reactant as the polycondensation reaction progresses or the temperature of the reactant rises above the set temperature, the stirring rate may be appropriately adjusted. The polycondensation reaction was performed until an intrinsic viscosity (IV) of the mixture (melt) in the reactor became 0.80 dl/g. When the intrinsic viscosity of the mixture in the reactor reached a desired level, the mixture was discharged out of the reactor and stranded. This was solidified with a cooling liquid and granulated to have an average weight of about 12 to 14 mg to prepare a polyester copolymer.

Example 2-7

[0087] r-BHET (1132.4 g), TPA (2220.2 g), EG (265.4 g), CHDM (1284.0 g), and ISB (156.2 g) were placed in a 10 L reactor to which a column, and a condenser capable of being cooled by water were connected, and GeO.sub.2 (1.0 g) as a catalyst, phosphoric acid (1.46 g) as a stabilizer, Polysynthren Blue RLS (manufactured by Clarient, 0.013 g) as a blue toner, and Solvaperm Red BB (manufactured by Clarient, 0.004 g) as a red toner were added thereto.

[0088] Then, nitrogen was injected into the reactor to form a pressurized state in which the pressure of the reactor was higher than normal pressure by 1.0 kgf/cm.sup.2 (absolute pressure: 1495.6 mmHg). Then, the temperature of the reactor was raised to 220 C. over 90 minutes, maintained at 220 C. for 2 hours, and then raised to 265 C. over 2 hours. Thereafter, an esterification reaction proceeded until the mixture in the reactor became transparent with the naked eye while maintaining the temperature of the reactor at 265 C. In this process, by-products flowed through the column and condenser. When the esterification reaction was completed, the nitrogen in the pressurized reactor was discharged to the outside to lower the pressure of the reactor to normal pressure, and then the mixture in the reactor was transferred to a 7 L reactor capable of vacuum reaction.

[0089] Then, the pressure of the reactor was reduced from normal pressure to 5 Torr (absolute pressure: 5 mmHg) over 30 minutes, and the temperature of the reactor was raised to 275 C. over 1 hour to proceed a polycondensation reaction while maintaining the pressure of the reactor at 1 Torr (absolute pressure: 1 mmHg) or less. In the initial stage of the polycondensation reaction, a stirring rate was set high, but when the stirring force is weakened due to an increase in the viscosity of the reactant as the polycondensation reaction progresses or the temperature of the reactant rises above the set temperature, the stirring rate may be appropriately adjusted. The polycondensation reaction was performed until an intrinsic viscosity (IV) of the mixture (melt) in the reactor became 0.65 dl/g. When the intrinsic viscosity of the mixture in the reactor reached a desired level, the mixture was discharged out of the reactor and stranded. This was solidified with a cooling liquid and granulated to have an average weight of about 12 to 14 mg to prepare a polyester copolymer.

Example 2-8

[0090] r-BHET (40.9 g), TPA (2643.1 g), EG (329.1 g), CHDM (1158.0 g), and ISB (587.0 g) were placed in a 10 L reactor to which a column, and a condenser capable of being cooled by water were connected, and GeO.sub.2 (1.0 g) as a catalyst, phosphoric acid (1.46 g) as a stabilizer, Polysynthren Blue RLS (manufactured by Clarient, 0.020 g) as a blue toner, and Solvaperm Red BB (manufactured by Clarient, 0.008 g) as a red toner were added thereto.

[0091] Then, nitrogen was injected into the reactor to form a pressurized state in which the pressure of the reactor was higher than normal pressure by 0.5 kgf/cm.sup.2 (absolute pressure: 1127.8 mmHg). Then, the temperature of the reactor was raised to 220 C. over 90 minutes, maintained at 220 C. for 2 hours, and then raised to 260 C. over 2 hours. Thereafter, an esterification reaction proceeded until the mixture in the reactor became transparent with the naked eye while maintaining the temperature of the reactor at 260 C. In this process, by-products flowed through the column and condenser. When the esterification reaction was completed, the nitrogen in the pressurized reactor was discharged to the outside to lower the pressure of the reactor to normal pressure, and then the mixture in the reactor was transferred to a 7 L reactor capable of vacuum reaction.

[0092] Then, the pressure of the reactor was reduced from normal pressure to 5 Torr (absolute pressure: 5 mmHg) over 30 minutes, and the temperature of the reactor was raised to 275 C. over 1 hour to proceed a polycondensation reaction while maintaining the pressure of the reactor at 1 Torr (absolute pressure: 1 mmHg) or less. In the initial stage of the polycondensation reaction, a stirring rate was set high, but when the stirring force is weakened due to an increase in the viscosity of the reactant as the polycondensation reaction progresses or the temperature of the reactant rises above the set temperature, the stirring rate may be appropriately adjusted. The polycondensation reaction was performed until an intrinsic viscosity (IV) of the mixture (melt) in the reactor became 0.80 dl/g. When the intrinsic viscosity of the mixture in the reactor reached a desired level, the mixture was discharged out of the reactor and stranded. This was solidified with a cooling liquid and granulated to have an average weight of about 12 to 14 mg to prepare a polyester copolymer.

Example 2-9

[0093] r-BHET (2930.2 g), TPA (1276.7.5 g), DMT (dimethyl terephthalate; 1492.0 g), EG (584.1 g), CHDM (221.5 g), and ISB (84.2 g) were placed in a 10 L reactor to which a column, and a condenser capable of being cooled by water were connected, and Mn(II) acetate tetrahydrate (1.5 g) and Sb.sub.2O.sub.3 (1.8 g) as a catalyst, and cobalt acetate (0.7 g) as a coloring agent were added thereto.

[0094] Then, nitrogen was injected into the reactor to bring the pressure of the reactor to normal pressure. Then, the temperature of the reactor was raised to 220 C. over 90 minutes, maintained at 220 C. for 2 hours, and then raised to 240 C. over 2 hours. Thereafter, an esterification reaction proceeded until the mixture in the reactor became transparent with the naked eye while maintaining the temperature of the reactor at 240 C. In this process, by-products flowed through the column and condenser. When the esterification reaction was completed, the nitrogen in the pressurized reactor was discharged to the outside to lower the pressure of the reactor to normal pressure, and then the mixture in the reactor was transferred to a 7 L reactor capable of vacuum reaction.

[0095] Then, the pressure of the reactor was reduced from normal pressure to 5 Torr (absolute pressure: 5 mmHg) over 30 minutes, and the temperature of the reactor was raised to 265 C. over 1 hour to proceed a polycondensation reaction while maintaining the pressure of the reactor at 1 Torr (absolute pressure: 1 mmHg) or less. In the initial stage of the polycondensation reaction, a stirring rate was set high, but when the stirring force is weakened due to an increase in the viscosity of the reactant as the polycondensation reaction progresses or the temperature of the reactant rises above the set temperature, the stirring rate may be appropriately adjusted. The polycondensation reaction was performed until an intrinsic viscosity (IV) of the mixture (melt) in the reactor became 0.60 dl/g. When the intrinsic viscosity of the mixture in the reactor reached a desired level, the mixture was discharged out of the reactor and stranded. This was solidified with a cooling liquid and granulated to have an average weight of about 12 to 14 mg.

[0096] The particles were allowed to stand at 150 C. for 1 hour to crystallize, and then put into a 20 L solid-phase polymerization reactor. Then, nitrogen was flowed into the reactor at a rate of 50 L/min. Herein, the temperature of the reactor was raised from room temperature to 140 C. at a rate of 40 C./hour, and maintained at 140 C. for 3 hours. Thereafter, the temperature was further raised to 200 C. at a rate of 40 C./hour, and maintained at 200 C. The solid-phase polymerization reaction was performed until the intrinsic viscosity (IV) of the particles in the reactor reached 0.95 dl/g to prepare a polyester copolymer.

Example 2-10

[0097] r-BHET (3461.1 g), TPA (969.4 g), IPA (isophthalic acid; 2262.0 g), EG (12.1 g), CHDM (140.2 g), and ISB (113.7 g) were placed in a 10 L reactor to which a column, and a condenser capable of being cooled by water were connected, and GeO.sub.2 (1.0 g) as a catalyst, and cobalt acetate (0.7 g) as a coloring agent were added thereto.

[0098] Then, nitrogen was injected into the reactor to form a pressurized state in which the pressure of the reactor was higher than normal pressure by 3.0 kgf/cm.sup.2 (absolute pressure: 2966.68 mmHg). Then, the temperature of the reactor was raised to 220 C. over 90 minutes, maintained at 220 C. for 2 hours, and then raised to 260 C. over 2 hours. Thereafter, an esterification reaction proceeded until the mixture in the reactor became transparent with the naked eye while maintaining the temperature of the reactor at 260 C. In this process, by-products flowed through the column and condenser. When the esterification reaction was completed, the nitrogen in the pressurized reactor was discharged to the outside to lower the pressure of the reactor to normal pressure, and then the mixture in the reactor was transferred to a 7 L reactor capable of vacuum reaction.

[0099] Then, the pressure of the reactor was reduced from normal pressure to 5 Torr (absolute pressure: 5 mmHg) over 30 minutes, and the temperature of the reactor was raised to 280 C. over 1 hour to proceed a polycondensation reaction while maintaining the pressure of the reactor at 1 Torr (absolute pressure: 1 mmHg) or less. In the initial stage of the polycondensation reaction, a stirring rate was set high, but when the stirring force is weakened due to an increase in the viscosity of the reactant as the polycondensation reaction progresses or the temperature of the reactant rises above the set temperature, the stirring rate may be appropriately adjusted. The polycondensation reaction was performed until an intrinsic viscosity (IV) of the mixture (melt) in the reactor became 0.60 dl/g. When the intrinsic viscosity of the mixture in the reactor reached a desired level, the mixture was discharged out of the reactor and stranded. This was solidified with a cooling liquid and granulated to have an average weight of about 12 to 14 mg.

[0100] The particles were allowed to stand at 150 C. for 1 hour to crystallize, and then put into a 20 L solid-phase polymerization reactor. Then, nitrogen was flowed into the reactor at a rate of 50 L/min. Herein, the temperature of the reactor was raised from room temperature to 140 C. at a rate of 40 C./hour, and maintained at 140 C. for 3 hours. Thereafter, the temperature was further raised to 190 C. at a rate of 40 C./hour, and maintained at 190 C. The solid-phase polymerization reaction was performed until the intrinsic viscosity (IV) of the particles in the reactor reached 1.0 dl/g to prepare a polyester copolymer.

Comparative Example 1

[0101] r-BHET (2441.8 g), TPA (1595.8 g), EG (101.3 g), CHDM (221.5 g), and ISB (98.2 g) were placed in a 10 L reactor to which a column, and a condenser capable of being cooled by water were connected, and GeO.sub.2 (1.0 g) as a catalyst and phosphoric acid (1.46 g) as a stabilizer were added thereto.

[0102] Then, nitrogen was injected into the reactor to form a pressurized state in which the pressure of the reactor was higher than normal pressure by 0.5 kgf/cm.sup.2 (absolute pressure: 1127.8 mmHg). Then, the temperature of the reactor was raised to 220 C. over 90 minutes, maintained at 220 C. for 2 hours, and then raised to 260 C. over 2 hours. Thereafter, an esterification reaction proceeded until the mixture in the reactor became transparent with the naked eye while maintaining the temperature of the reactor at 260 C. In this process, by-products flowed through the column and condenser. When the esterification reaction was completed, the nitrogen in the pressurized reactor was discharged to the outside to lower the pressure of the reactor to normal pressure, and then the mixture in the reactor was transferred to a 7 L reactor capable of vacuum reaction.

[0103] Then, the pressure of the reactor was reduced from normal pressure to 5 Torr (absolute pressure: 5 mmHg) over 30 minutes, and the temperature of the reactor was raised to 280 C. over 1 hour to proceed a polycondensation reaction while maintaining the pressure of the reactor at 1 Torr (absolute pressure: 1 mmHg) or less. In the initial stage of the polycondensation reaction, a stirring rate was set high, but when the stirring force is weakened due to an increase in the viscosity of the reactant as the polycondensation reaction progresses or the temperature of the reactant rises above the set temperature, the stirring rate may be appropriately adjusted. The polycondensation reaction was performed until an intrinsic viscosity (IV) of the mixture (melt) in the reactor became 0.60 dl/g. When the intrinsic viscosity of the mixture in the reactor reached a desired level, the mixture was discharged out of the reactor and stranded. This was solidified with a cooling liquid and granulated to have an average weight of about 12 to 14 mg.

[0104] The particles were allowed to stand at 150 C. for 1 hour to crystallize, and then put into a 20 L solid-phase polymerization reactor. After maintaining at 100 mmHg for 1 hour, nitrogen was flowed into the reactor at a rate of 50 L/min. Herein, the temperature of the reactor was raised from room temperature to 140 C. at a rate of 40 C./hour, and maintained at 140 C. for 3 hours. Thereafter, the temperature was further raised to 200 C. at a rate of 40 C./hour, and maintained at 200 C. The solid-phase polymerization reaction was performed until the intrinsic viscosity (IV) of the particles in the reactor reached 0.70 dl/g to prepare a polyester copolymer.

Comparative Example 2

[0105] r-BHET (4232.9 g), TPA (691.6 g), EG (406.8 g), CHDM (150.0 g), and ISB (106.4 g) were placed in a 10 L reactor to which a column, and a condenser capable of being cooled by water were connected, and GeO.sub.2 (1.0 g) as a catalyst, phosphoric acid (1.46 g) as a stabilizer and cobalt acetate (0.7 g) as a coloring agent were added thereto.

[0106] Then, nitrogen was injected into the reactor to form a pressurized state in which the pressure of the reactor was higher than normal pressure by 1.0 kgf/cm.sup.2 (absolute pressure: 1495.6 mmHg). Then, the temperature of the reactor was raised to 220 C. over 90 minutes, maintained at 220 C. for 2 hours, and then raised to 260 C. over 2 hours. Thereafter, an esterification reaction proceeded until the mixture in the reactor became transparent with the naked eye while maintaining the temperature of the reactor at 260 C. In this process, by-products flowed through the column and condenser. When the esterification reaction was completed, the nitrogen in the pressurized reactor was discharged to the outside to lower the pressure of the reactor to normal pressure, and then the mixture in the reactor was transferred to a 7 L reactor capable of vacuum reaction.

[0107] Then, the pressure of the reactor was reduced from normal pressure to 5 Torr (absolute pressure: 5 mmHg) over 30 minutes, and the temperature of the reactor was raised to 280 C. over 1 hour to proceed a polycondensation reaction while maintaining the pressure of the reactor at 1 Torr (absolute pressure: 1 mmHg) or less. In the initial stage of the polycondensation reaction, a stirring rate was set high, but when the stirring force is weakened due to an increase in the viscosity of the reactant as the polycondensation reaction progresses or the temperature of the reactant rises above the set temperature, the stirring rate may be appropriately adjusted. The polycondensation reaction was performed until an intrinsic viscosity (IV) of the mixture (melt) in the reactor became 0.60 dl/g. When the intrinsic viscosity of the mixture in the reactor reached a desired level, the mixture was discharged out of the reactor and stranded. This was solidified with a cooling liquid and granulated to have an average weight of about 12 to 14 mg.

[0108] The particles were allowed to stand at 150 C. for 1 hour to crystallize, and then put into a 20 L solid-phase polymerization reactor. Then, nitrogen was flowed into the reactor at a rate of 50 L/min. Herein, the temperature of the reactor was raised from room temperature to 140 C. at a rate of 40 C./hour, and maintained at 140 C. for 3 hours. Thereafter, the temperature was further raised to 200 C. at a rate of 40 C./hour, and maintained at 200 C. The solid-phase polymerization reaction was performed until the intrinsic viscosity (IV) of the particles in the reactor reached 0.95 dl/g to prepare a polyester copolymer.

Comparative Example 3

[0109] r-BHET (934.5 g), TPA (2443.0 g), EG (558.9 g), CHDM (794.7 g), and ISB (26.9 g) were placed in a 10 L reactor to which a column, and a condenser capable of being cooled by water were connected, and Ge.sub.2O (1.0 g) as a catalyst, phosphoric acid (1.46 g) as a stabilizer, Polysynthren Blue RLS (manufactured by Clarient, 0.012 g) as a blue toner, and Solvaperm Red BB (manufactured by Clarient, 0.004 g) as a red toner were added thereto.

[0110] Then, nitrogen was injected into the reactor to form a pressurized state in which the pressure of the reactor was higher than normal pressure by 0.5 kgf/cm.sup.2 (absolute pressure: 1127.8 mmHg). Then, the temperature of the reactor was raised to 220 C. over 90 minutes, maintained at 220 C. for 2 hours, and then raised to 255 C. over 2 hours. Thereafter, an esterification reaction proceeded until the mixture in the reactor became transparent with the naked eye while maintaining the temperature of the reactor at 255 C. In this process, by-products flowed through the column and condenser. When the esterification reaction was completed, the nitrogen in the pressurized reactor was discharged to the outside to lower the pressure of the reactor to normal pressure, and then the mixture in the reactor was transferred to a 7 L reactor capable of vacuum reaction.

[0111] Then, the pressure of the reactor was reduced from normal pressure to 5 Torr (absolute pressure: 5 mmHg) over 30 minutes, and the temperature of the reactor was raised to 280 C. over 1 hour to proceed a polycondensation reaction while maintaining the pressure of the reactor at 1 Torr (absolute pressure: 1 mmHg) or less. In the initial stage of the polycondensation reaction, a stirring rate was set high, but when the stirring force is weakened due to an increase in the viscosity of the reactant as the polycondensation reaction progresses or the temperature of the reactant rises above the set temperature, the stirring rate may be appropriately adjusted. The polycondensation reaction was performed until an intrinsic viscosity (IV) of the mixture (melt) in the reactor became 0.75 dl/g. When the intrinsic viscosity of the mixture in the reactor reached a desired level, the mixture was discharged out of the reactor and stranded. This was solidified with a cooling liquid and granulated to have an average weight of about 12 to 14 mg to prepare a polyester copolymer.

Comparative Example 4

[0112] r-BHET (705.1 g), TPA (2249.8 g), EG (1214.9 g), and CHDM (95.4 g) were placed in a 10 L reactor to which a column, and a condenser capable of being cooled by water were connected, and Ge.sub.2O (1.0 g) as a catalyst, phosphoric acid (1.46 g) as a stabilizer, Polysynthren Blue RLS (manufactured by Clarient, 0.010 g) as a blue toner, and Solvaperm Red BB (manufactured by Clarient, 0.003 g) as a red toner were added thereto.

[0113] Then, nitrogen was injected into the reactor to form a pressurized state in which the pressure of the reactor was higher than normal pressure by 0.1 kgf/cm.sup.2 (absolute pressure: 833.6 mmHg). Then, the temperature of the reactor was raised to 220 C. over 90 minutes, maintained at 220 C. for 2 hours, and then raised to 260 C. over 2 hours. Thereafter, an esterification reaction proceeded until the mixture in the reactor became transparent with the naked eye while maintaining the temperature of the reactor at 260 C. In this process, by-products flowed through the column and condenser. When the esterification reaction was completed, the nitrogen in the pressurized reactor was discharged to the outside to lower the pressure of the reactor to normal pressure, and then the mixture in the reactor was transferred to a 7 L reactor capable of vacuum reaction.

[0114] Then, the pressure of the reactor was reduced from normal pressure to 5 Torr (absolute pressure: 5 mmHg) over 30 minutes, and the temperature of the reactor was raised to 270 C. over 1 hour to proceed a polycondensation reaction while maintaining the pressure of the reactor at 1 Torr (absolute pressure: 1 mmHg) or less. In the initial stage of the polycondensation reaction, a stirring rate was set high, but when the stirring force is weakened due to an increase in the viscosity of the reactant as the polycondensation reaction progresses or the temperature of the reactant rises above the set temperature, the stirring rate may be appropriately adjusted. The polycondensation reaction was performed until an intrinsic viscosity (IV) of the mixture (melt) in the reactor became 0.65 dl/g. When the intrinsic viscosity of the mixture in the reactor reached a desired level, the mixture was discharged out of the reactor and stranded. This was solidified with a cooling liquid and granulated to have an average weight of about 12 to 14 mg.

[0115] The particles were allowed to stand at 150 C. for 1 hour to crystallize, and then put into a 20 L solid-phase polymerization reactor. Then, nitrogen was flowed into the reactor at a rate of 50 L/min. Herein, the temperature of the reactor was raised from room temperature to 140 C. at a rate of 40 C./hour, and maintained at 140 C. for 3 hours. Thereafter, the temperature was further raised to 220 C. at a rate of 40 C./hour, and maintained at 220 C. The solid-phase polymerization reaction was performed until the intrinsic viscosity (IV) of the particles in the reactor reached 0.85 dl/g to prepare a polyester copolymer.

[0116] The results are shown in Table 2 below.

TABLE-US-00002 TABLE 2 YID of r-BHET Yellow Plaque solution r-BHET CHDM ISB IV Factor Color L-b Unit wt % mol % mol % dg/l Ex. 2-1 5 30 8 2 0.70 1.5 91.5 Ex. 2-2 7 75 5 2 0.95 5.2 87.8 Ex. 2-3 10.5 92 4 0 0.80 9.7 83.3 Ex. 2-4 13 14 5 0 0.85 1.8 91.2 Ex. 2-5 15 50 30 0 0.70 7.5 85.5 Ex. 2-6 1 30 20 0 0.80 0.3 92.7 Ex. 2-7 3 22 50 3 0.65 0.7 92.3 Ex. 2-8 7.5 1 50 15 0.80 0.1 92.9 Ex. 2-9 12.5 59 8 2 0.95 7.3 85.7 Ex. 2-10 10 75 5 2 1.00 7.5 85.5 Comparative Ex. 1 25 58 8 2 0.70 14.4 78.6 Comparative Ex. 2 15.5 77 5 2 0.95 11.9 81.1 Comparative Ex. 3 50 21 30 1 0.75 10.4 82.6 Comparative Ex. 4 60 18 0 4 0.85 10.9 82.1 1) (YID of BHET solution) * (BHET content)/100

[0117] As shown in Table 2, it was confirmed that the yellow factor of 10 or less had good color quality, whereas the yellow factor exceeding 10 had deteriorated color quality. Considering this together with the result of Example 1 above, it could be confirmed that physical properties of the polyester copolymer using r-BHET can be predicted by measuring the YID of the r-BHET solution.