Method for preparing multi-purpose biodegradable polyester resin having low melting point, and polyester resin for yarn and fiber, prepared thereby

Abstract

The present invention relates to a method for preparing a multi-purpose biodegradable polyester resin having a low melting point, and a polyester resin for yarn and fiber, prepared thereby. According to the present invention, the biodegradable polyester resin can be prepared using an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid. Here, monomer esterification is performed stepwise to prepare a block copolymer rather than a random copolymer, thereby enabling biodegradability to be improved. In addition, when the present invention is used, the biodegradable polyester resin can be prepared to have a high molecular weight, excellent physical properties such as chromaticity and flexibility, a low melting point and excellent producibility, and, since fiberization is easy, the biodegradable polyester resin can be effectively used for various applications such as clothes, shoes and non-woven fabrics.

Description

Method for producing a multipurpose biodegradable low-melting-point polyester resin and polyester resin for yarn and fiber produced thereby

[0001] The present invention relates to a method for producing a multipurpose biodegradable low-melting polyester resin and a polyester resin for yarn and fiber produced thereby, and more particularly, to a method for producing a multipurpose polyester resin having excellent biodegradability, high molecular weight, low melting point, and excellent physical properties such as transparency and flexibility and productivity, and a polyester resin for yarn and fiber produced thereby.

[0002] Plastics are polymeric synthetic resins that are utilized in a wide range of fields due to their superior physical properties and productivity. For example, aromatic polyester resins such as polyethylene terephthalate (PET) resin boast exceptional strength, wear resistance, and stability, making them widely used in the manufacture of containers for beverages, cosmetics, films, and sheets. However, PET resin is a non-biodegradable resin, taking approximately 500 years to decompose when buried in soil, seriously contributing to environmental pollution.

[0003] Meanwhile, aliphatic polyester resins, unlike PET, do not contain benzene rings within their molecules, demonstrating excellent biodegradability. However, they face the limitation of being more difficult to increase their degree of polymerization compared to aromatic polyester resins. Generally, for polyester resins to be fiberizable, their molecular weight must be at least 20,000, and for diverse applications, it must be at least 30,000. However, increasing the molecular weight of aliphatic polyester resins is difficult, hindering their application to diverse products and fields.

[0004] To overcome the limitations of aliphatic polyester resins, Korean Patent Publication No. 1998-028015 describes a technique for manufacturing aliphatic polyester and then reacting it with polyisocyanate to increase its molecular weight. However, this method suffers from long reaction times, resulting in low productivity. Furthermore, the polyisocyanate used as a chain extender is highly toxic to the human body.

[0005] To address the shortcomings of the aforementioned aliphatic and aromatic resins, polyester resins incorporating both aliphatic and aromatic monomers are being studied. Polybutylene adipate terephthalate (PBAT) is one example. For example, Republic of Korea Patent Publication No. 10-2024-0047326 describes a technique for manufacturing biodegradable resin molded products using polybutylene adipate terephthalate.

[0006] The above PBAT resin has the advantage of being biodegradable and can be used in daily necessities such as disposable plastic bottles, toothbrushes, and razors, but has the limitation of being somewhat stiff and not soft enough to be used as a fiber.

[0007] Therefore, there is a need to develop a polyester resin that exhibits excellent biodegradability like aliphatic polyester resins, has a high molecular weight like aromatic polyester resins, and has excellent transparency, flexibility, and other properties, as well as high productivity, so that it can be used for various purposes such as fibers.

[0008] The purpose of the present invention is to provide a method for producing a multipurpose biodegradable polyester resin having excellent biodegradability, high molecular weight, excellent transparency, flexibility, and other properties, a low melting point, and excellent productivity.

[0009] Another object of the present invention is to provide a polyester resin manufactured by the above manufacturing method and usable for yarn and fiber.

[0010] In order to achieve the above object, the present invention provides a method for producing a biodegradable polyester resin, comprising the steps of: reacting an aromatic dicarboxylic acid or a derivative thereof, an aliphatic dicarboxylic acid, a polyhydric alcohol, a catalyst, and a stabilizer in a monomer reactor to perform a monomer esterification reaction; and transporting a product of the monomer esterification reaction to a polymer reactor to perform a polymerization reaction, thereby producing a polyester resin.

[0011] In the present invention, the monomer esterification reaction step may include a first monomer esterification step of adding an aromatic dicarboxylic acid or a derivative thereof, a polyhydric alcohol, and a first catalyst to a monomer reactor and reacting the same; and a second monomer esterification step of adding an aliphatic dicarboxylic acid, a second catalyst, and a first stabilizer to the reaction product of the first monomer esterification step and reacting the same.

[0012] At this time, before transferring to the polymer reactor, a step of adding a third catalyst and a second stabilizer to the reaction product of the second monomer esterification step may be further performed.

[0013] In the present invention, the aromatic dicarboxylic acid or derivative thereof may include at least one selected from the group consisting of dimethyl terephthalate, terephthalic acid, isophthalic acid, dimethyl isophthalate, 2,6-naphthalenedicarboxylic acid, and derivatives thereof.

[0014] In the present invention, the aliphatic dicarboxylic acid may include at least one selected from the group consisting of succinic acid, adipic acid, oxalic acid, malonic acid, glutaric acid, pimelic acid, terbric acid, azelaic acid, and sebacic acid.

[0015] In the present invention, the molar ratio of the aromatic dicarboxylic acid or its derivative and the aliphatic dicarboxylic acid may be 1:0.1 to 1:1.

[0016] In the present invention, the polyhydric alcohol may include at least one selected from the group consisting of ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,4-cyclohexanedimethanol, diethylene glycol, 1,3-propanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanediol, 1,8-octanediol, and trimethylol propane.

[0017] In the present invention, the polyhydric alcohol may be added in an amount of 1 to 3 moles per mole of the aromatic dicarboxylic acid or derivative thereof.

[0018] In the present invention, the first, second and third catalysts may each independently include at least one selected from the group consisting of tetrabutyl titanate, titanium dioxide, titanium chelate, tetra-ethyl titanate, tetra-n-propyl titanate, tetra-isopropyl titanate, butyl isopropyl titanate, dibutyl tin oxide, manganese acetate, cobalt acetate, calcium acetate and zinc acetate.

[0019] In the present invention, the first and second stabilizers may each independently include at least one selected from the group consisting of phosphorous acid, phosphoric acid, trimethylphosphate, triethylphosphate, triphenylphosphate, neopentyldiaryloxytriphosphate, and triethylphosphonoacetate.

[0020] In the present invention, the first and second monomer esterification steps can be performed by raising the reaction temperature so that the final reaction temperature becomes 180 to 250°C.

[0021] In the present invention, the first and second monomer esterification steps can be performed for a total of 200 to 400 minutes.

[0022] In the present invention, the polymerization reaction can be performed at a temperature range of 200 to 300°C.

[0023]

[0024] The present invention can also provide a biodegradable polyester resin for yarn and fiber manufactured by the above manufacturing method.

[0025] In the present invention, the intrinsic viscosity of the polyester resin may be 1.5 to 2.0 dl / g.

[0026] According to the present invention, a low-melting-point polyester resin can be manufactured using aromatic and aliphatic dicarboxylic acid monomers, and by performing the monomer esterification reaction step by step, a block copolymer rather than a random copolymer can be manufactured, thereby improving biodegradability. Furthermore, using the present invention, a biodegradable polyester resin having a high molecular weight, excellent physical properties such as color and flexibility, and high productivity can be manufactured, and since it can be fiberized, it can be usefully used in various applications such as clothing, shoes, and non-woven fabrics.

[0027] Figure 1 shows the chemical structure of a polyester resin manufactured according to one embodiment of the present invention.

[0028] Figure 2 is a schematic diagram of the internal section of the Ubbelodhe viscosity tube used in one embodiment of the present invention.

[0029] Figure 3 shows the results of tensile strength analysis of a polyester resin manufactured according to one embodiment of the present invention.

[0030] Figure 4 shows a photograph of the results of manufacturing a fiber using a polyester resin manufactured according to one embodiment of the present invention.

[0031] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description is provided solely to facilitate understanding of embodiments of the present invention and is not intended to limit the scope of protection.

[0032]

[0033] The present invention relates to a method for producing a multipurpose polyester resin that has excellent biodegradability, high molecular weight, low melting point, and excellent color, flexibility, and other properties, and can be applied to various fields, particularly yarn and fiber.

[0034] The polyester resin according to the present invention can be manufactured through a step of performing a monomer esterification reaction by reacting an aromatic dicarboxylic acid or a derivative thereof, an aliphatic dicarboxylic acid, a polyhydric alcohol, a catalyst, and a stabilizer in a monomer reactor; and a step of transporting the product of the monomer esterification reaction to a polymer reactor to perform a polymerization reaction.

[0035] In the present invention, the monomer esterification reaction step may be performed through a first monomer esterification step of adding an aromatic dicarboxylic acid or a derivative thereof, a polyhydric alcohol, and a first catalyst to a monomer reactor and reacting the same; and a second monomer esterification step of adding an aliphatic dicarboxylic acid, a second catalyst, and a first stabilizer to the reaction product of the first monomer esterification step and reacting the same.

[0036] By performing the monomer esterification reaction step by step in this way, a block copolymer rather than a random copolymer is formed, thereby improving the biodegradability of the polyester resin. Furthermore, the present invention can produce a polyester resin having a high molecular weight, excellent physical properties such as color and flexibility, and easy fiberization.

[0037]

[0038] Reaction raw materials

[0039]

[0040] In the present invention, a monomer esterification reaction is performed using an aromatic dicarboxylic acid or a derivative thereof, an aliphatic dicarboxylic acid, and a polyhydric alcohol as ester reaction raw materials.

[0041] Specifically, a block copolymer can be manufactured by first reacting an aromatic dicarboxylic acid or a derivative thereof with a polyhydric alcohol, and then performing a secondary reaction by adding an aliphatic dicarboxylic acid.

[0042] The aromatic dicarboxylic acid or derivative thereof used in the present invention may include at least one selected from the group consisting of dimethyl terephthalate, terephthalic acid, isophthalic acid, dimethyl isophthalate, 2,6-naphthalenedicarboxylic acid, and derivatives thereof.

[0043] The aliphatic dicarboxylic acid used in the present invention may include at least one aliphatic dicarboxylic acid compound having 3 to 20 carbon atoms, and specifically may include at least one selected from the group consisting of succinic acid, adipic acid, oxalic acid, malonic acid, glutaric acid, pimelic acid, servicic acid, azelaic acid, and sebacic acid.

[0044] In the present invention, the molar ratio of the aromatic dicarboxylic acid or its derivative and the aliphatic dicarboxylic acid may be 1:0.1 to 1:1, preferably 1:0.2 to 1:0.8, and specifically 1:0.3 to 1:0.5.

[0045] Preferably, a copolymer resin can be manufactured by mixing two or more aliphatic dicarboxylic acids. This can overcome the disadvantages of using only one type of acid raw material.

[0046] For example, when using only succinic acid as the acid raw material, biodegradability is exhibited, but fiberization is difficult. Similarly, when using only adipic acid, the resin may have weak strength and a low melting point, which can lead to processing difficulties. To address these shortcomings, a copolymer resin can be produced by mixing succinic acid and adipic acid, thereby obtaining a biodegradable polyester resin with excellent flexibility and strength.

[0047] Therefore, in a preferred embodiment of the present invention, the aliphatic dicarboxylic acid may include succinic acid and adipic acid. In this case, the succinic acid and adipic acid may be used in a molar ratio of 1:5 to 1:50, preferably 1:10 to 1:30.

[0048] In the present invention, the dicarboxylic acid reacts with a polyhydric alcohol to form an ester monomer.

[0049] The polyhydric alcohol usable in the present invention may include at least one selected from the group consisting of ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,4-cyclohexanedimethanol, diethylene glycol, 1,3-propanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanediol, 1,8-octanediol, and trimethylol propane.

[0050] In the present invention, the polyhydric alcohol may be used in an amount of 1 to 3 moles, preferably 1.1 to 2.5 moles, specifically 1.5 to 2 moles, and more specifically 1.7 to 1.9 moles, relative to 1 mole of the aromatic dicarboxylic acid or its derivative. In addition, the polyhydric alcohol may be used in an amount of 2 to 10 moles, preferably 2 to 8 moles, specifically 3 to 6 moles, and more specifically 4 to 5 moles, relative to 1 mole of the aliphatic dicarboxylic acid.

[0051] If the amount of polyhydric alcohol used is less than the above range, it may be difficult to obtain a resin with a high molecular weight due to the small amount of alcohol. On the other hand, if the polyhydric alcohol is used in excessive amounts, the reaction time may be prolonged and the manufacturing cost may increase.

[0052]

[0053] Catalysts and stabilizers

[0054]

[0055] In the present invention, in addition to the dicarboxylic acid and polyhydric alcohol, a catalyst and / or stabilizer may be added to obtain a resin with high strength and high viscosity.

[0056] As a catalyst usable in the present invention, at least one selected from the group consisting of tetrabutyl titanate, titanium dioxide, titanium chelate, tetra-ethyl titanate, tetra-n-propyl titanate, tetra-isopropyl titanate, butyl isopropyl titanate, dibutyl tin oxide, manganese acetate, cobalt acetate, calcium acetate, and zinc acetate may be used. Preferably, two to three types of catalysts may be mixed and used, and for example, two types of catalysts may be mixed and used in a molar ratio of 1:0.1 to 1:0.5.

[0057] In the present invention, the catalyst may be added in an amount of 10 to 1,200 ppm based on the weight of the total reactant.

[0058] As a stabilizer usable in the present invention, a stabilizer used in a general polyester polymerization reaction can be used, and at least one stabilizer selected from the group consisting of phosphorous acid, phosphoric acid, trimethylphosphate, triethylphosphate, triphenylphosphate, neopentyldiaryloxytriphosphate, and triethylphosphonoacetate can be used, and preferably, two or more types can be mixed and used.

[0059] In the present invention, the stabilizer may be added in an amount of 10 to 500 ppm based on the weight of the total reactant.

[0060]

[0061] Monomer esterification reaction

[0062]

[0063] In the present invention, the aromatic dicarboxylic acid or a derivative thereof, an aliphatic dicarboxylic acid, and a polyhydric alcohol are reacted in the presence of a catalyst and a stabilizer to perform a monomer esterification reaction, and then the product is polymerized (polymerized) to produce a polyester resin.

[0064] The above esterification reaction is a reaction that condenses a dicarboxylic acid and a polyhydric alcohol to produce an ester monomer, and is performed by introducing raw materials and increasing the temperature within the reactor. The monomer esterification reaction is advantageous when it proceeds quickly, and the reaction can be performed at a stirring speed of 100 to 500 rpm, for example, 150 to 300 rpm.

[0065] As the temperature inside the reactor rises and the reaction begins, water is produced as a reaction byproduct between 160 and 180°C. The time from the start of the reaction until the first drop of the byproduct is produced is called the initial point (IP).

[0066] In the present invention, during the esterification reaction, the reaction temperature is preferably increased at a rate of 5 to 10°C per minute from the starting point, and the rate of increase is preferably reduced to 3 to 5°C per minute from the initial point. If the temperature is increased at the same rate during the esterification reaction, polyhydric alcohol may leak out and cause scattering, and byproducts may cause problems such as difficulty in polymerization during the polymerization reaction.

[0067] After the initial point, the reaction can be continued at a temperature of 180°C or higher, preferably 180 to 250°C, more preferably 190 to 240°C, and even more preferably 190 to 220°C. The reaction time from the start of the reaction to the completion of the reaction can be 200 to 400 minutes, and specifically, the reaction can be carried out for 300 to 380 minutes.

[0068] In monomer reactions, it is desirable to block oxygen during the process to control the color and strength of the resin. This oxygen blocking is preferably performed not only during the monomer reaction but also throughout the entire process, including the steps of adding reactants to the monomer reactor, the monomer reaction, transferring the monomer reaction to the polymer reactor, the polymerization reaction, and the product discharge. From this perspective, nitrogen is preferably used for vacuum breaking and discharge pressure. Blocking oxygen throughout the process prevents oxidation of the reactants and prevents fires caused by gases that may be generated during the reaction.

[0069] In the present invention, the monomer esterification reaction step may be performed through a first monomer esterification step of adding an aromatic dicarboxylic acid or a derivative thereof, a polyhydric alcohol, and a first catalyst to a monomer reactor and reacting the same; and a second monomer esterification step of adding an aliphatic dicarboxylic acid, a second catalyst, and a first stabilizer to the reaction product of the first monomer esterification step and reacting the same.

[0070] Preferably, a step (third step) of adding a third catalyst and a second stabilizer to the reaction product of the second monomer esterification step before transferring it to the polymer reactor is further performed, and the product is immediately dropped into the polymer reactor to proceed with the polymerization reaction.

[0071] In the above embodiment, the first monomer esterification step may be performed for 180 to 300 minutes, specifically 200 to 250 minutes, and the second monomer esterification step may be performed for 80 to 150 minutes, specifically 100 to 130 minutes. In addition, the temperature of the first monomer esterification step and the temperature of the second monomer esterification step may be the same or different, and the temperature difference between each step may be 0 to 20°C.

[0072] In the present invention, by separately introducing an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid, a block copolymer rather than a random copolymer is formed, thereby producing a resin having excellent biodegradability, and the resin produced thereby can exhibit various physical properties such as high molecular weight, excellent color, and flexibility.

[0073] The monomer reaction is terminated when the theoretical amount of by-product is discharged, the top temperature of the column drops, and the internal temperature rises.

[0074]

[0075] polymerization

[0076]

[0077] The ester monomer produced by the above monomer esterification reaction is transferred to a polymer reactor to perform a polymerization reaction.

[0078] At this time, the transfer to the polymer reactor can be performed in a dropping manner. Specifically, the monomer reactor is positioned above the polymer reactor, and after the monomer reaction is completed, the bottom valve of the monomer reactor is opened to allow the transfer in a natural dropping manner. At this time, it is necessary to preheat the transfer line to approximately 200°C to prevent the monomer from solidifying during transfer. The transferred monomer is stirred at a low speed of 10 to 20 rpm for approximately 10 minutes to stabilize it.

[0079] The above polymerization reaction can be carried out at a temperature of 200 to 300°C, preferably 220 to 260°C, and more preferably 230 to 240°C. In addition, the total polymerization reaction time can be 120 to 300 minutes, specifically 150 to 280 minutes.

[0080] The above polymerization reaction requires vacuum conditions. However, if the vacuum is applied too quickly, the monomer may fly away and reach the condenser. This can clog the condenser, reduce the vacuum level, and hinder polymerization. Therefore, to minimize flying, it is advisable to carefully apply a low vacuum.

[0081] In the above vacuum control, by inputting an electronic mutation program so that the pressure drops from normal pressure (740 to 760 mmHg) to reduced pressure (5 to 20 mmHg) over a period of 20 to 40 minutes, the vacuum can be precisely applied to prevent scattering. After dropping the pressure to a low vacuum state, it is preferable to drop the pressure again to full vacuum (0 to 1 mmHg) over a period of 10 to 20 minutes from the perspective of preventing scattering.

[0082] In the present invention, it is important to control the stirring speed of the polymerization reaction. In the initial stage of the polymerization reaction, it is preferable to perform stirring at a high speed, with the stirring speed set to 30 to 70 rpm, preferably 40 to 60 rpm.

[0083] In one embodiment of the present invention, the agitator may be decelerated before reaching the load power value. This deceleration may be performed one or more times, and is preferably performed three to five times. The amount of speed reduction may be adjusted within the range of 5 to 20 rpm for each deceleration. Specifically, when starting stirring at a speed of 60 rpm, the speed may be decelerated to 40 rpm and then sequentially changed to 30 rpm, 20 rpm, and 10 rpm, thereby producing a high molecular weight, high viscosity resin.

[0084] In a preferred embodiment of the present invention, stirring can be performed using a pole change motor. A pole change motor is a motor used when changing the speed of an induction motor into several stages. In an induction motor, the rotational speed is determined by the number of poles of the motor and the frequency of the power source, so the rotational speed can be controlled by changing the wiring of the motor to combine two types of poles and changing the circuit. If the pole change motor does not increase power any further at a power level of about 30 kW and hunting occurs, it is preferable to carry out the polymerization reaction by controlling the stirring speed by changing the poles in advance at a power level of 15 to 20 kW before reaching 30 kW.

[0085] When a polyester resin is produced through a polymerization reaction, the resin inside the polymer reactor is discharged and dried.

[0086]

[0087] Properties and uses of polyester resin

[0088]

[0089] According to the method of the present invention, a polyester resin with excellent biodegradability and easy fiberization can be produced. For example, the polyester resin produced according to the present invention may be polybutylene adipate succinate terephthalate (PBAST) resin, the chemical structure of which can be represented as shown in Figure 1.

[0090] According to the present invention, a high molecular weight polyester resin having an intrinsic viscosity of 0.8 dl / g or more, preferably 1.0 dl / g or more, more preferably 1.5 to 2.0 dl / g, and even more preferably 1.7 to 2.0 dl / g can be produced. As such, since the polyester resin of the present invention has a high intrinsic viscosity, it can exhibit properties such as being thin, strong, and suitable for twisting without breaking when fiberized.

[0091] In the experimental examples of the present invention, it was confirmed that a polyester resin having a very high intrinsic viscosity of up to 1.725 dl / g can be produced through the step-by-step reaction of utilizing aliphatic and aromatic dicarboxylic acids, optimizing catalysts and stabilizers, and monomer esterification.

[0092] The weight average molecular weight (Mw) of the polyester resin manufactured according to the present invention may be 30,000 to 200,000, preferably 50,000 to 120,000.

[0093] In addition, the polyester resin produced by the method of the present invention may have an L* (white) value of 60 or more, preferably 70 or more, more preferably 75 or more, and even more preferably 80 or more among color coordinates, and a b* (yellow) value of 15 or less, preferably 10 or less, and even more preferably 5 or less. In this way, by using the method of the present invention, a polyester resin having high transparency and low yellowness and excellent color can be produced.

[0094] The melting point of the polyester resin manufactured according to the present invention may be 120°C or higher and 200°C or lower, preferably 140°C or higher, more preferably 150°C or higher, and even more preferably 155°C or higher. The polyester resin of the present invention may exhibit the advantage of easy molding due to its low melting point. In addition, the melt index may be 2 to 30, preferably 3 to 20, and may exhibit properties advantageous for fiberization.

[0095] The method of the present invention allows the production of a polyester resin with superior biodegradability, molecular weight, color, productivity, and other properties. The polyester resin of the present invention is easily fiberized and has a softer, silkier feel than conventional polyethylene terephthalate resins. Furthermore, its spinning temperature is 160 to 170°C, much lower than that of polyethylene terephthalate (280°C), resulting in lower power loss and thus being desirable from a carbon neutrality perspective.

[0096] Accordingly, the polyester resin of the present invention is biodegradable and can be used in the production of yarn and fiber. Therefore, the present invention can be usefully applied to a variety of applications requiring fiberization and biodegradability, such as clothing, footwear, fishing lines, fishing nets, and nonwoven fabrics.

[0097]

[0098] Example

[0099]

[0100] Hereinafter, the present invention will be described in more detail through examples. It will be apparent to those skilled in the art that these examples are intended solely to illustrate the present invention and are not intended to limit the scope of the present invention.

[0101]

[0102] Manufacturing example: Polyester resin manufacturing

[0103]

[0104] According to the raw materials in Table 1 and the reaction conditions in Table 2, polyester resins of Examples 1 to 5 and Comparative Examples 1 to 3 were manufactured.

[0105]

[0106]

[0107]

[0108]

[0109]

[0110] Example 1: Preparation of PBAST resin

[0111]

[0112] Dimethyl terephthalate (DMT) 418 kg, succinic acid (SA) 4.84 kg, adipic acid (AA) 114.9 kg, 1,4-butandiol (1,4-BD) 349 kg, catalyst tetrabutyltitanate (TBT) 335 g, tetra-isopropyl titanate (TPT) 53.1 g, stabilizer trimethyl phosphoric acid (TMP) 253.1 g, and phosphorous acid (PA) 53.1 g were weighed and prepared.

[0113] The esterification reactor was preheated to 50°C, and half of the 1,4-BD was introduced through the diaphragm. Then, 253.1 g of DMT, catalysts (TBT and TPT), stabilizer (TMP), and 53.1 g of PA were sequentially introduced. The remaining 1,4-BD was then introduced into the ES furnace, the diaphragm was closed, and a nitrogen atmosphere was created by gently introducing nitrogen for about 1 minute before the reaction began.

[0114] During the reaction, the reactor stirring speed was set to 200 rpm from beginning to end, and the reaction temperature was increased at a rate of 5 to 10°C per minute, and when the point at which by-products were produced (the initial point) was reached, the temperature was reduced to 3 to 5°C per minute, and the reaction was terminated under the conditions of a reaction temperature of 230°C and a reaction time of 350 minutes.

[0115] The pressure was precisely reduced from 750 mmHg to 10 mmHg using an electronic valve for 30 minutes in a low-vacuum system, and the vacuum valve was slowly opened from 10 mmHg to 0.5 mmHg over 15 minutes to initiate the polyester reaction. Afterwards, the molecular weight was increased as desired by controlling the stirring speed (pole change) and pelletizing was performed.

[0116]

[0117] Example 2: Preparation of PBAST resin

[0118]

[0119] In Example 1, aliphatic monomers and aromatic monomers were introduced simultaneously to carry out a random copolymerization reaction, whereas in Example 2, aliphatic monomers and aromatic monomers were introduced separately to carry out an ester reaction in order to produce a block copolymer, and were reacted together during the polymer reaction.

[0120]

[0121] Example 3: Preparation of PBAST resin

[0122]

[0123] The raw material and input process of the monomer reaction were carried out in the same manner as in Example 2, but 53.1 g of calcium acetate (CA) was added as a catalyst.

[0124]

[0125] Example 4: Preparation of PBAST resin

[0126]

[0127] The raw material and input process of the monomer reaction were carried out in the same manner as in Example 2, but 53.1 g of tetrapropyl titanate (TPT) was added as a catalyst to perform polymerization.

[0128]

[0129] Example 5: Preparation of PBAST resin

[0130]

[0131] The raw materials and input process of the monomer reaction were the same as in Example 4, but 53.1 g of calcium acetate (CA) as a catalyst and 53.1 g of phosphorous acid (PA) as a stabilizer were added to perform polymerization.

[0132]

[0133] Comparative Example 1: PET Resin Manufacturing

[0134]

[0135] A typical polyester polymerization was performed under polyethylene terephthalate (PET) conditions. Because the reaction occurs rapidly in the case of PET aromatics, the amount of catalyst was reduced.

[0136] Dimethyl terephthalate (DMT) 418 kg, ethylene glycol (EG) 200.32 kg, tetrabutyl titanate (TBT) catalyst 111.5 g, calcium acetate (CA) 53.1 g, and trimethyl phosphate (TMP) stabilizer 15.93 g were weighed and prepared. After adding dimethyl terephthalate, the catalyst and stabilizer were added, and then ethylene glycol was added and an esterification reaction was performed at normal pressure. During the polymer reaction, by removing byproducts and increasing the molecular weight while performing the polymerization reaction from low vacuum to high vacuum, polyethylene terephthalate (PET) resin was manufactured.

[0137]

[0138] Comparative Example 2: PBT resin production

[0139]

[0140] Compared to Comparative Example 1, 291 g of 1,4-BD was used instead of EG, and the reaction conditions were adjusted as shown in Table 2 to manufacture polybutylene terephthalate (PBT) resin.

[0141]

[0142] Comparative Example 3: Preparation of PBAT resin

[0143]

[0144] A biodegradable copolymer, polybutylene adipate terephthalate (PBAT), was prepared by carrying out a polymerization reaction using dimethyl terephthalate (DMT), 1,4-butanediol (1,4-BD), adipic acid (AA), a catalyst tetrabutyl titanate (TBT), and a stabilizer trimethyl phosphate (TMP) in the amounts shown in Table 1 and the reaction conditions shown in Table 2.

[0145]

[0146] Experimental Example 1: Measurement of the physical properties of polyester resin

[0147]

[0148] For the polyester resins of the examples and comparative examples, the physical properties of the resins were measured using the following method.

[0149] In the case of biodegradability, the decomposition rate was evaluated as biodegradability compared to cellulose (100%) after 6 months of landfill (Certified Evaluation Testing Agency: Korea Research Institute of Chemical Technology (KRICT)).

[0150] In order to measure the intrinsic viscosity, the resins of the examples and comparative examples were dissolved in o-chlorophenol at a concentration of 1.28 g / dl. Using an Ubbelodhe viscosity tube and maintaining the water bath temperature at 30°C, the time taken for the solution to pass between sections a - b inside the viscosity tube as shown in Fig. 2 is t, and the time taken for the solvent to pass (Efflux time) is t0, and the specific viscosity (η) is calculated by the following mathematical formula 1. SP ) was calculated.

[0151] [Mathematical Formula 1]

[0152]

[0153]

[0154] Specific viscosity (η) calculated by mathematical formula 1 SP ), the intrinsic viscosity (η) was calculated using the following mathematical equation 2. In mathematical equation 2, A is the Huggins constant, which is 0.247, and C is the concentration value, which is 1.2 dl / g.

[0155] [Equation 2]

[0156]

[0157]

[0158] Additionally, the L* (white) and b* (yellow) values ​​in the CIE-L*a*b* colorimetric system were measured using a colorimeter, and the amount (g) of resin flowing through an orifice for 10 minutes at a temperature of 190°C and a load of 2,160 g was measured and recorded as the melt index (MI) according to ASTM D1238.

[0159] The properties of polyester resin measured according to the above method are shown in Table 3 below.

[0160]

[0161] ClassificationBiodegradabilityIntrinsic viscosity(dl / g)Color(L* / b*)Melting point(℃)Melting index(MI)Example 195% or more1.260 / 1512080Example 290% or more1.6676 / 515730Example 390% or more1.6878 / 415920Example 490% or more1.70580 / 415815Example 595% or more1.72582 / 3160.426.6Comparative example Within 11%0.63570 / 6255N / AComparative example Within 21%0.64075 / 5220N / AComparative example 390%1.40381 / 316010

[0162]

[0163] Referring to the above experimental results, the PBAST resin manufactured according to the present invention exhibited biodegradability, unlike PET and PBT resins, while having a higher molecular weight and better color, productivity, and workability, and also exhibited superior molecular weight characteristics compared to the PBAT resin.

[0164]

[0165] In addition, compared to the resin of Example 1 in which aromatic dicarboxylic acid, aliphatic dicarboxylic acid, and polyhydric alcohol were polymerized simultaneously, the resins of Examples 2 to 5, which were manufactured through block copolymerization by separately introducing aliphatic and aromatic monomers and then performing esterification reactions step by step, exhibited higher intrinsic viscosity, better color characteristics, and a melt index suitable for fiberization. In particular, when two or more types of catalysts were combined and an additional stabilizer was introduced, physical properties such as biodegradability, intrinsic viscosity, and color could be further improved.

[0166] Accordingly, it was confirmed that the polyester resin manufactured using the present invention has excellent biodegradability, high molecular weight, and other excellent physical properties.

[0167]

[0168] Experimental Example 2: Tensile Strength Analysis of Polyester Resin

[0169]

[0170] The elongation characteristics of the PBAST resin of Example 5 were analyzed using a universal testing machine (UTM) at 50 mm / min. For comparison, the same test was performed on the existing PBAT resin (Solpol 1000H), and the results are shown in Fig. 3.

[0171] Referring to Figure 3, it can be seen that the PBAST resin manufactured using the present invention exhibits superior tensile strength and elongation compared to conventional PBAT. Combining the results of this experiment with the results of Experimental Example 1, it can be confirmed that the present invention can produce a polyester resin with a higher molecular weight and superior tensile strength and elongation compared to PBAT resin.

[0172]

[0173] Experimental Example 3: Analysis of the physical properties of polyester fibers

[0174]

[0175] A fiber was produced through filament spinning using the PBAST resin of Example 5 above.

[0176] Figure 4 shows a photograph of the manufactured fiber, and the diameter, linear density, linear denier, tenacity, and breaking elongation were measured for the fiber, and the results are shown in Table 4 below.

[0177]

[0178] Physical property standard result Fiber diameter (mm) 0.12 ± 0.02 0.116 Linear density (dtex) 122 ± 2.0 120 Linear denier CV (%) ≤ 5.0 4.3 Tenacity (cN / dtex) ≥ 2.0 1.9 Elongation at break (%) 22.0 ± 4.0 21.9

[0179]

[0180] Referring to the above experimental results, it was confirmed that the polyester resin produced according to the present invention is easy to spin into fiber, and the produced fiber exhibits strength and elongation that meet the required conditions.

[0181] Accordingly, it was found that the resin of the present invention can be usefully applied to various fields requiring fiberization, such as clothing, shoes, and non-woven fabrics.

[0182]

[0183] Although some implementation forms of the present invention have been described above, the present invention is not limited to the implementation forms described above, and can be implemented by modifying and changing them within a scope that does not deviate from the gist of the present invention, and it should be understood that forms with such modifications and changes also fall within the technical spirit of the present invention.

Claims

1. A first monomer esterification step of adding an aromatic dicarboxylic acid or a derivative thereof, a polyhydric alcohol, and a first catalyst to a monomer reactor and reacting them; A second monomer esterification step of adding and reacting an aliphatic dicarboxylic acid, a second catalyst, and a first stabilizer to the reaction product of the first monomer esterification step; and A step of manufacturing a polyester resin by transporting the reaction product of the second monomer esterification step to a polymer reactor and performing a polymerization reaction. A method for producing a biodegradable polyester resin, comprising:

2. In paragraph 1, Before transferring to the polymer reactor, A method for producing a biodegradable polyester resin, further comprising the step of adding a third catalyst and a second stabilizer to the reaction product of the second monomer esterification step.

3. In paragraph 1, A method for producing a biodegradable polyester resin, wherein the aromatic dicarboxylic acid or a derivative thereof comprises at least one selected from the group consisting of dimethyl terephthalate, terephthalic acid, isophthalic acid, dimethyl isophthalate, 2,6-naphthalenedicarboxylic acid, and derivatives thereof.

4. In paragraph 1, A method for producing a biodegradable polyester resin, wherein the aliphatic dicarboxylic acid comprises at least one selected from the group consisting of succinic acid, adipic acid, oxalic acid, malonic acid, glutaric acid, pimelic acid, terbric acid, azelaic acid, and sebacic acid.

5. In paragraph 1, A method for producing a biodegradable polyester resin, wherein the molar ratio of the aromatic dicarboxylic acid or a derivative thereof and the aliphatic dicarboxylic acid is 1:0.1 to 1:

1.

6. In paragraph 1, A method for producing a biodegradable polyester resin, wherein the polyhydric alcohol comprises at least one selected from the group consisting of ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,4-cyclohexanedimethanol, diethylene glycol, 1,3-propanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanediol, 1,8-octanediol, and trimethylol propane.

7. In paragraph 1, A method for producing a biodegradable polyester resin, wherein 1 to 3 mol of the above polyhydric alcohol is added per 1 mol of the aromatic dicarboxylic acid or its derivative.

8. In paragraph 1, A method for producing a biodegradable polyester resin, wherein the first and second catalysts each independently include at least one selected from the group consisting of tetrabutyl titanate, titanium dioxide, titanium chelate, tetra-ethyl titanate, tetra-n-propyl titanate, tetra-isopropyl titanate, butyl isopropyl titanate, dibutyl tin oxide, manganese acetate, cobalt acetate, calcium acetate, and zinc acetate.

9. In paragraph 1, A method for producing a biodegradable polyester resin, wherein the first stabilizer comprises at least one selected from the group consisting of phosphorous acid, phosphoric acid, trimethylphosphate, triethylphosphate, triphenylphosphate, neopentyldiaryloxytriphosphate, and triethylphosphonoacetate.

10. In paragraph 1, A method for producing a biodegradable polyester resin, wherein the first and second monomer esterification steps are performed by raising the reaction temperature so that the final reaction temperature becomes 180 to 250°C.

11. In paragraph 1, A method for producing a biodegradable polyester resin, wherein the first and second monomer esterification steps are performed for a total of 200 to 400 minutes.

12. In paragraph 1, A method for producing a biodegradable polyester resin, wherein the polymerization reaction is performed at a temperature range of 200 to 300°C.

13. A biodegradable polyester resin for fibers manufactured by the method of any one of claims 1 to 12.

14. In paragraph 13, A biodegradable polyester resin for fibers, wherein the intrinsic viscosity of the polyester resin is 1.5 to 2.0 dl / g.

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