Process for the preparation of poly(ether ester) copolymers

Abstract

The present invention provides a method for preparing a poly(ether ester) copolymer, and more particularly, a method for preparing a poly(ether ester) copolymer having a high polyether content and a high viscosity by using a dicarboxylic acid as a raw material. According to the present invention, a poly(ether ester) copolymer having a high polyether content and a high viscosity is prepared using a dicarboxylic acid having a low production cost as a raw material without solid-phase polymerization.

Description

TECHNICAL FIELD

[0001] Cross Reference to Related Applications

[0002] This application claims the benefit of Korean Patent Application No. 10-2017-0158925, filed November 24, 2017, and Korean Patent Application No. 10-2018-0130140, filed October 29, 2018, the entire contents of both of which are incorporated herein by reference.

[0003] The present invention relates to a method of preparing a poly(ether ester) copolymer, and more particularly, to a method of preparing a poly(ether ester) copolymer having a high polyether content and a low hardness property and having a high viscosity by using a dicarboxylic acid as a raw material. BACKGROUND

[0004] Thermoplastic poly(ether ester) elastomers (TPEE) are high-performance materials having both the elasticity of rubber and the mold processing property of plastic. TPEE is a substitute for vulcanized rubber and PVC (polyvinyl chloride), and is used in many fields such as automobiles, home appliances, building materials, IT, daily necessities, etc. A representative of TPEE is a poly(ether ester) block copolymer resin composition.

[0005] A poly(ether ester) copolymer has an elastic property by including a hard segment consisting of a diol and a dicarboxylic acid and a soft segment consisting of a polyether diol and a dicarboxylic acid. The hard segment provides mechanical properties to the elastomer, and the soft segment provides elasticity and flexibility to the elastomer.

[0006] These thermoplastic poly(ether ester) copolymers are commercially prepared by a two-step reaction including an ester exchange reaction of a diol, a dicarboxylic acid ester, and a polyether diol as raw materials, and then a polycondensation reaction of the reaction product.

[0007] For example, as one well-known TPEE, a polybutylene terephthalate (PBT)-poly(tetramethylene ether glycol) (PTMG) copolymer is prepared using 1,4-butanediol (BG), dimethyl terephthalate (DMT), and PTMG as raw materials by an ester exchange reaction and a polycondensation reaction.

[0008] Meanwhile, a method of using a corresponding dicarboxylic acid instead of a dicarboxylic acid ester has been developed. In this case, an esterification reaction occurs instead of an ester exchange reaction, and water is generated as a byproduct instead of an alcohol. For example, a PBT-PTMG copolymer can be prepared using terephthalic acid (PTA) instead of DMT as a raw material, and has an advantage in terms of economic efficiency since the production cost of PTA is lower than that of DMT.

[0009] However, when the raw material is simply replaced with a dicarboxylic acid in the conventional method using a dicarboxylic acid ester, there is a problem that esterification does not occur properly, thereby reducing productivity. This phenomenon becomes more serious as the content of polyether glycol in the raw material is higher. Therefore, it is difficult to produce a poly(ether ester) copolymer having a high polyether content and a low hardness by the known dicarboxylic acid ester process.

[0010] To solve this problem, it has been proposed that when preparing a PBT-PTMG copolymer, BG is first reacted with PTA to prepare a prepolymer, which is then reacted with PTMG (Chinese J. Polym. Sci. 33 (2015) 1283-1293). However, this preparation method has a problem that esterification becomes complicated in two steps. In addition, in order to increase the viscosity of a low hardness poly(ether ester) copolymer, a solid phase polymerization reaction must be further performed after the polycondensation reaction. Therefore, the preparation process becomes complicated and is not suitable for mass production.

[0011] Therefore, there is a need for a method of preparing a poly(ether ester) copolymer in a simple and economical manner, thereby being suitable for mass production, in which a poly(ether ester) copolymer having a high viscosity while having a low hardness performance due to a high polyether content is prepared using a dicarboxylic acid as a raw material.

[0012] [Citation List]

[0013] Non-Patent Literature 1: Chinese J. Polym. Sci. 33 (2015) 1283-1293 SUMMARY

[0014] TECHNICAL PROBLEM

[0015] An object of the present application is to provide a method of preparing a poly(ether ester) copolymer having a high polyether content while having a low hardness and a high viscosity by using a dicarboxylic acid as a raw material without a solid phase polymerization.

[0016] TECHNICAL SOLUTION

[0017] To solve the above problem, the present application provides a method of preparing a high viscosity poly(ether ester) copolymer having a polyether content of 60 to 90% by weight and an intrinsic viscosity of more than 2.0 at 25°C, the method comprising:

[0018] a) an esterification step of reacting a dihydric alcohol, a dicarboxylic acid, and a polyether glycol in the presence of a catalyst;

[0019] b) a first polycondensation step of further adding a catalyst to the reaction mixture of step a) and performing polycondensation under reduced pressure to prepare a prepolymer; and

[0020] c) a second polycondensation step of polycondensing the prepolymer under a pressure condition lower than the pressure of step b),

[0021] wherein the molar ratio of diol / dicarboxylic acid added in step a) is greater than 2.5, and the amount of catalyst added in step a) and step b) is 50 ppm or more, respectively, based on active metal.

[0022] Step a) can be performed in a reactor equipped with a distillation column maintained at 80°C to 150°C.

[0023] Step a) can be performed under conditions of a temperature of 150°C to 300°C and a pressure of 100 torr to 760 torr.

[0024] Step b) can be performed under conditions of a temperature of 180°C to 250°C and a pressure of greater than 5 torr and 100 torr or less.

[0025] Step c) can be performed under conditions of a temperature of 180°C to 250°C and a pressure of 5 torr or less.

[0026] The total amount of catalyst added in step a) and step b) can be less than 500 ppm.

[0027] The number average molecular weight of the polyether diol can be 500 g / mol to 3000 g / mol.

[0028] Preferably, the intrinsic viscosity of the poly(ether ester) copolymer at 25°C can be 2.2 or more.

[0029] The melt flow index of the poly(ether ester) copolymer can be 12 g / 10 min or less, measured according to ASTM D1238.

[0030] The Shore D hardness of the poly(ether ester) copolymer can be 40 or less.

[0031] Advantageous effects

[0032] According to the present application, a poly(ether ester) copolymer having a low hardness and a high polyether content and having a high intrinsic viscosity of greater than 2.0 is produced using a dicarboxylic acid having a low production cost as a raw material without solid phase polymerization. DETAILED DESCRIPTION

[0033] The terms used in the present specification are used only to describe exemplary embodiments, and are not intended to limit the present application. Singular expressions can include plural expressions unless they are differently expressed in the context. It is to be understood that the terms "include", "comprise" or "have" used in the present specification are merely meant to denote presence of features, steps, components or combinations thereof described in the specification, and do not preclude the possibility of additional one or more features, steps, components or combinations thereof.

[0034] The present application can be variously modified and has various forms, and specific examples will be exemplified and explained in detail below. However, it is not intended to limit the present application to the specific examples, and it should be understood that the present application includes all modifications, equivalents or alternatives included in the spirit and technical scope of the present application.

[0035] Hereinafter, the present application will be described in detail.

[0036] The present application provides a method for preparing a high viscosity poly(ether ester) copolymer having a polyether content of 60 to 90 wt% and an intrinsic viscosity of 2.0 or more at 25°C, the method comprising:

[0037] a) an esterification step of reacting a dihydric alcohol, a dicarboxylic acid and a polyether diol in the presence of a catalyst;

[0038] b) a first polycondensation step of further adding a catalyst to the reaction mixture of step a) and performing polycondensation under reduced pressure to prepare a prepolymer; and

[0039] c) a second polycondensation step of performing polycondensation of the prepolymer under a pressure lower than that of step b),

[0040] wherein the molar ratio of the dihydric alcohol / dicarboxylic acid added in step a) is greater than 2.5, and the amount of the catalyst added in steps a) and b) is 50 ppm or more, respectively, based on the active metal.

[0041] According to the preparation method of the present application, a cheap dicarboxylic acid is used instead of a dicarboxylic acid ester as a raw material, thereby preparing a high viscosity poly(ether ester) copolymer having a high polyether content and a low hardness property and having an intrinsic viscosity of greater than 2.0 without changing a known dicarboxylic acid ester process.

[0042] The preparation method of the present application can be performed using a dicarboxylic acid with a conventional dicarboxylic acid ester production apparatus or a conventional PBT production apparatus, and can not require both esterification and solid state polymerization steps, thereby greatly reducing production costs and process operation costs and improving productivity. Accordingly, the preparation method of the present application is suitable for mass production.

[0043] In the present application, the thermoplastic poly(ether ester) copolymer can be prepared by esterifying a diol, a dicarboxylic acid, and a polyether diol as raw materials in the presence of a catalyst, transferring the obtained reaction mixture to a separate polycondensation reactor, and then polycondensing the reaction mixture in the presence of a catalyst.

[0044] In the present application, the diol is an aliphatic or alicyclic diol having 2 to 10 carbon atoms and a molecular weight of 300 g / mol or less, which is preferable in terms of achieving the effects of the present application. Specifically, examples of the diol that can be used in the present application can include aliphatic diols such as 1,4-butanediol, monoethylene glycol, diethylene glycol, propylene glycol, neopentyl glycol, and the like; and alicyclic diols such as 1,1-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, tricyclodecane dimethanol, and the like, but are not limited thereto. Specifically, in the present application, the diol can be 1,4-butanediol.

[0045] Examples of the dicarboxylic acid that can be used in the present application can include terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, adipic acid, and sebacic acid, but are not limited thereto. Specifically, the dicarboxylic acid can be terephthalic acid.

[0046] In the preparation method of the present application, the diol and the dicarboxylic acid are included in a specific content ratio, so that even in the absence of solid-phase polymerization, a poly(ether ester) copolymer having a low hardness property can have a high viscosity by including 60% by weight or more of a polyether. That is, in order to prepare a poly(ether ester) copolymer having a low hardness and a high viscosity in the absence of solid-phase polymerization, the molar ratio of the diol / dicarboxylic acid added in the esterification step of the present application can be in the range of greater than 2.5, 2.6 or more, or 2.8 or more, and 4 or less, 3.7 or less, or 3.5 or less.

[0047] As such, only when the molar ratio of the diol / dicarboxylic acid exceeds 2.5, a low hardness poly(ether ester) copolymer having a high viscosity and a polyether content of 60% to 90% by weight can be prepared even in the absence of solid-phase polymerization.

[0048] The "low hardness" property is a property obtained when the poly(ether ester) copolymer has a polyether content of 60% by weight or more. Specifically, when the Shore D hardness of the copolymer is 40 or less, and preferably when the Shore D hardness is 35 or less, it is considered to be a low hardness poly(ether ester) copolymer. The lower limit of the hardness of the low hardness poly(ether ester) copolymer can be, but is not particularly limited to, for example, Shore D of 20 or more, or Shore D of 25 or more. The poly(ether ester) copolymer having a low hardness property can be more appropriately applied to a gripping member of an IT device, a high-elasticity fiber, or the like.

[0049] Meanwhile, the reference value of "high viscosity" is different according to the hardness properties of the poly(ether ester) copolymer, and the reference value of "high viscosity" of the low hardness poly(ether ester) copolymer is higher than that of the high hardness poly(ether ester) copolymer. Specifically, when the intrinsic viscosity of the high hardness poly(ether ester) copolymer having a polyether content of less than 60 wt% at 25°C is about 1.2 or more, it can be considered that the copolymer satisfies the high viscosity property. However, when the intrinsic viscosity of the low hardness poly(ether ester) copolymer having a polyether content of 60 wt% or more, which is prepared according to the preparation method of the present application, at 25°C is greater than 2.0, it can be considered that the copolymer satisfies the high viscosity property. Preferably, the intrinsic viscosity of the poly(ether ester) copolymer prepared according to the present application at 25°C is greater than 2.0, and more preferably 2.2 or more.

[0050] Meanwhile, even if the molar ratio of the diol / dicarboxylic acid exceeds 4, a high viscosity copolymer can be prepared. However, there is a disadvantage in that energy consumption in the polycondensation reaction increases in order to remove the excess diol. Therefore, the molar ratio is preferably 4 or less.

[0051] Meanwhile, the poly(ether ester) copolymer finally prepared in the present application satisfies a polyether content in the range of 60 wt% to 90 wt% or 70 wt% to 90 wt%. When the above range is satisfied, there is an effect of preparing a low hardness poly(ether ester) copolymer.

[0052] The polyether content in the prepared copolymer can be controlled by controlling the amount of the polyether diol added for esterification. Specifically, in order to obtain the polyether content in the above range, the amount of the polyether diol as a raw material can be 35 wt% to 90 wt% or 40 wt% to 85 wt% with respect to the total of 100 wt% of the raw materials consisting of the diol, the dicarboxylic acid, and the polyether diol.

[0053] The polyether diol that can be used in the present application can be in the form of a homopolymer or a copolymer, and specific examples thereof can include one or more selected from the group consisting of polytetramethylene glycol, polyethylene glycol, polypropylene glycol, polyethylene glycol-polypropylene glycol-polyethylene glycol, and polyhexamethylene glycol, but are not limited thereto. Specifically, the polyether diol can be polytetramethylene glycol.

[0054] In this regard, the number average molecular weight (Mn) of the polyether diol is not particularly limited, but when the number average molecular weight (Mn) is in the range of 500 g / mol to 3000 g / mol, 1000 g / mol to 2500 g / mol, or 1500 g / mol to 2200 g / mol, it is suitable for preparing a poly(ether ester) copolymer having a polyether content of 60% by weight or more, and is preferred in terms of ensuring the effects of the present application. The number average molecular weight can be determined by, for example, gel permeation chromatography (GPC) or end group titration (in which the end groups of the polyether diol are acetylated using acetic anhydride, the unreacted acetic anhydride is decomposed into acetic acid, the OH value of the acetylated polyether diol is determined by back titration using a base, and the number average molecular weight of the polyether diol is determined from the OH value) or OH end group titration. 1 H NMR analysis.

[0055] The esterification reaction of the dihydric alcohol, the dicarboxylic acid, and the polyether diol can be performed in the presence of a catalyst. In this regard, a substance known in the art can be appropriately used as the catalyst. Specifically, the catalyst can be a catalyst including titanium or tin as an active metal, and more specifically, the catalyst can include a titanium-based catalyst such as tetrabutyl titanate (TBT), tetraethyl titanate, and tetra(isopropyl) titanate, or a tin-based catalyst such as n-butyl stannic acid, octyl stannic acid, dimethyl tin oxide, dibutyl tin oxide, dioctyl tin oxide, diphenyl tin oxide, tri-n-butyl tin acetate, tri-n-butyl tin chloride, or tri-n-butyl tin fluoride. In addition, in addition to the above-described catalysts, a catalyst such as an oxide or acetate including Mg, Ca, Mn, Zn, Pb, or Zr as an active metal can be used alone or in combination. Among them, a titanium-based catalyst such as TBT can be preferably used.

[0056] Meanwhile, in the present application, the catalyst is added in the polycondensation step as well as in the esterification reaction.

[0057] Generally, in the process of preparing a poly(ether ester) copolymer, the catalysts for the esterification (or transesterification) reaction and the polycondensation reaction are the same as each other. Since a separate process is not included between the two reactions, a predetermined amount of the catalyst is added at the beginning or during the reaction of the first esterification (or transesterification) reaction, and then the catalyst can not be further added in the polycondensation step.

[0058] However, the experimental results of the present inventors confirmed that, in order to prepare a poly(ether ester) copolymer having a high polyether diol content and a high viscosity, it is preferable to batch and separately add the catalyst to the esterification reaction step and the polycondensation reaction step. Accordingly, in the present application, the catalyst is batched and separately added to the esterification reaction step and the first polycondensation reaction step.

[0059] Specifically, 50 ppm or more of the catalyst is added, based on the active metal of the catalyst, with respect to the total weight of the raw materials, before the start of the esterification step of step a) and the first polycondensation step of step b), more specifically, 50 ppm to 250 ppm or 100 ppm to 200 ppm of the catalyst is added in step a) and step b), respectively. In this regard, preferably, the total amount of the catalyst added in step a) and step b), based on the active metal, is not more than 500 ppm. If the amount of the catalyst used in each step is less than 50 ppm, the progress of the reaction will be slowed due to the lack of the catalyst, and if the total amount of the catalyst exceeds 500 ppm, a side reaction will occur or the catalyst will remain as an impurity in the product. Therefore, the amount of the catalyst is appropriately controlled within the above range.

[0060] Hereinafter, each step of the preparation method of the present application will be described.

[0061] Step a) of the present application is a step of esterifying a diol, a dicarboxylic acid, and a polyether diol in the presence of a catalyst, in which esterification occurs between the diol and the dicarboxylic acid or between the polyether diol and the dicarboxylic acid to produce water and tetrahydrofuran (THF) as by-products.

[0062] To achieve the above effects of the present application, the appropriate reaction temperature of step a) is in the range of 150°C to 300°C or 200°C to 240°C, and the appropriate reaction pressure of step a) is in the range of 100 torr or more to less than 760 torr, 100 torr to 500 torr, or 200 torr to 400 torr. Specifically, after the raw materials and the catalyst are added to the reactor, the temperature is increased at 0.1°C / min to 10°C / min under stirring until the temperature reaches the above temperature range, and then the esterification can be performed for about 30 minutes to 4 hours or 1 hour to 2 hours.

[0063] Since esterification is a reversible reaction, water and THF as by-products must be removed to ensure that the forward reaction (formation of an ester bond) continuously occurs. However, when the raw material diol is evaporated together in this process, loss of the raw material will occur, and the molar ratio of the diol / dicarboxylic acid for obtaining a high-viscosity poly(ether ester) copolymer cannot be ensured. Therefore, a method of removing water and THF while minimizing the evaporation of the diol is required.

[0064] To this end, in the present application, as described above, step a) can be performed under a reduced pressure of 100 torr or more to less than 760 torr, 100 torr to 500 torr, or 200 torr to 400 torr, and in a reactor equipped with a distillation column maintained at 80°C to 180°C or 100°C to 150°C. Under these conditions, the conversion rate of the esterification reaction can be greatly improved, and a low-hardness poly(ether ester) copolymer having a high polyether content can be produced. If the reaction is performed under atmospheric pressure (760 torr), the evaporation rate of the diol decreases, but the conversion rate of the esterification decreases, and thus, it is difficult to sufficiently increase the viscosity of the poly(ether ester) copolymer. If the reaction is performed under a reduced pressure without a distillation column, the evaporation rate of the diol is too high, and thus, there is a problem in that the molar ratio of the diol / dicarboxylic acid cannot be maintained at 2.5 or more.

[0065] In this regard, the distillation column is preferably a packed column or a plate column. More specifically, a structured packed column is preferred.

[0066] When step a) is completed, the polycondensation reactions of steps b) and c) are performed. The polycondensation steps can be performed in a reactor separate from the esterification reactor, and can be performed without a distillation column. Specifically, the polycondensation steps can be performed after further adding a catalyst in an amount of 50 ppm or more based on the active metal to the reaction mixture in which step a) is completed.

[0067] In the present application, the polycondensation steps can be divided into two steps of b) and c). In essence, steps b) and c) are sequentially performed, but there are differences in the pressure conditions. Specifically, step b) is a process for removing excess diol, and step c) is a process for increasing the viscosity of the poly(ether ester) copolymer.

[0068] Step b) of the present application is a first polycondensation step performed under relatively mild conditions, in which a catalyst is further added to the reaction mixture of step a), and then polycondensation is performed under reduced pressure while stirring to obtain a prepolymer.

[0069] The pressure at which step b) is performed is preferably in the range of greater than 5 torr and 100 torr or less, or 10 torr to 50 torr, and the temperature at which step b) is performed is preferably in the range of 180°C to 250°C, or 230°C to 250°C. Under these conditions, excess unreacted diol in step a) is evaporated and removed. The reaction time of step b) can be, but is not particularly limited to, about 20 minutes to about 1 hour, or about 20 minutes to about 40 minutes.

[0070] If the polycondensation reaction is directly performed under high vacuum of 5 torr or less without performing step b), rapid evaporation of unreacted dihydric alcohol occurs to cause bumping in the reactor, and the decrease in the temperature of the reactants is accelerated. In addition, there is a problem in that it is difficult to obtain a high viscosity poly(ether ester) copolymer. Therefore, in the present application, a first polycondensation step is preliminarily performed under mild conditions before the polycondensation reaction is performed.

[0071] Meanwhile, in step a) or step b), one or more commonly used additives can be added together to improve the reaction efficiency and control the physical properties of the prepared poly(ether ester) copolymer.

[0072] Examples of the applicable additives can include: a branching agent (e.g., glycerol, sorbitol, pentaerythritol, 1,1,4,4-tetra(hydroxymethyl)cyclohexane, trimethylolpropane, pyromellitic acid, 1,1,2,2-ethanetetracarboxylic acid, etc.) for improving the melt strength of the poly(ether ester) copolymer; a matting agent (e.g., TiO2, zinc sulfide, or zinc oxide) for improving the color characteristics; a colorant (e.g., a dye); a stabilizer (e.g., an antioxidant, an ultraviolet stabilizer, a heat stabilizer, etc.); a filler; a flame retardant; a pigment; an antibacterial agent; an antistatic agent; a fluorescent brightener; a processing aid; a tackifier; etc., and any one of them or a mixture of two or more of them can be used, but are not limited thereto. For example, in order to improve the thermal stability of the poly(ether ester) copolymer, a stabilizer such as a hindered phenol (e.g., Irganox 1098) can be added.

[0073] Each of the additives can be used in an appropriate amount within a range in which the physical properties of the prepared poly(ether ester) copolymer are not deteriorated while the desired effect is secured. Specifically, the amount of each of the additives can be 0.1 to 10% by weight, relative to 100% by weight of the total raw materials.

[0074] Step c) is a reaction performed continuously after step b), and is a step of polycondensing the prepolymer in the same reactor only by reducing the pressure. If the temperature at which step c) is performed is too high, such as more than 250°C, the high viscosity properties of the prepared poly(ether ester) copolymer can even be deteriorated, and thus, preferably, the temperature satisfies the above range. More preferably, the reaction temperature of step c) can be less than 250°C.

[0075] In addition, the pressure at which step c) is performed is lower than the pressure at which step b) is performed, and is preferably in the range of 5 torr or less or 0.5 to 3 torr.

[0076] Under the above conditions, the polycondensation reaction is performed for about 30 minutes to 5 hours or 1 hour to 3 hours, and when the torque value reaches 1.5 to 3.0 Nm, the reaction is terminated to finally prepare the poly(ether ester) copolymer.

[0077] The poly(ether ester) copolymer prepared by the above method has a polyether content of up to 60% to 90% by weight, preferably 70% to 90% by weight. Therefore, the poly(ether ester) copolymer is characterized by a Shore hardness (Shore D) of less than 40, and preferably 20 to 35. Due to the low hardness of the poly(ether ester) copolymer, the copolymer prepared by the present invention can exhibit excellent flexibility.

[0078] Furthermore, according to the preparation method of the present invention, poly(ether ester) copolymers with high viscosity and high polyether content can be prepared solely through esterification and polycondensation reactions without solid-state polymerization. In other words, the poly(ether ester) copolymers prepared by the present invention have a high intrinsic viscosity of greater than 2.0, greater than 2.1, or 2.3 to 4.0 at 25°C. In addition, the melt flow index (MI) of the poly(ether ester) copolymer, measured according to ASTM D1238, is less than 12 g / 10 min, preferably less than 10 g / 10 min.

[0079] According to the present invention, poly(ether ester) copolymers with high viscosity and high polyether content can be prepared from inexpensive dicarboxylic acids using conventional equipment previously used for the preparation of poly(ether ester) copolymers via a simple process. Therefore, the present invention is suitable for large-scale production and industrial-scale processing, and can improve the economic efficiency and productivity of the process.

[0080] Preferred examples will be provided below to better understand the invention. However, the embodiments below are for illustrative purposes only, and those skilled in the art will understand that various changes and modifications can be made without departing from the scope and spirit of the invention, and such changes and modifications fall within the scope of the appended claims.

[0081] [Example]

[0082] Example 1

[0083] 20 parts by weight of terephthalic acid (PTA), 33 parts by weight of 1,4-butanediol (BG), and 47 parts by weight of polytetramethylene glycol (PTMG) (M n =2000) and 50 ppm (based on Ti) of TBT catalyst were added to a 2 L glass reactor, and the temperature was raised to 200 °C over 1 hour with stirring under a nitrogen atmosphere. The molar ratio of BG / PTA was 3.0, and PTMG was used to make the polyether content in the PBT-PTMG copolymer 69% by weight.

[0084] The esterification (ES) reaction was performed at 200 to 230°C and 300 torr for 2 hours. At this time, a reflux condenser and a Dean-Stark separator, which were maintained at 120°C, were installed in the reactor instead of a distillation column, and the ES reaction was performed. After the reaction was completed, the conversion of the esterification calculated using the difference in the density of the water and THF mixture collected in the Dean-Stark separator was 97% by the following mathematical equation 1.

[0085] [mathematical equation 1]

[0086] (1) THF generation amount (ml)

[0087] = (volume of the collection in the separator - weight of the collection in the separator) / (density of H2O - density of THF)

[0088] (2) Theoretical H2O generation amount (ml) accompanying THF generation

[0089] = THF generation amount * THF density / THF molecular weight * molecular weight of H2O

[0090] (3) Theoretical H2O generation amount (ml) of the esterification reaction

[0091] = PTA addition amount / PTA molecular weight * molecular weight of H2O * density of H2O * 2

[0092] (4) Conversion rate (%) of the ES reaction = (amount of the collection in the separator - (1) + (2)) / (3) * 100

[0093] After the ES reaction, 50 ppm of a Ti catalyst and 3000 ppm of Irganox 1098 as an antioxidant were added to the reactor. After the reflux condenser was removed, a first polycondensation (PP) reaction was performed at 230 to 240°C under a reduced pressure of 10 torr for 30 minutes.

[0094] A second polycondensation (PC) reaction was performed at 235 to 240°C for 3 hours under 1 torr or less. During the PC reaction, the torque value of the mechanical stirrer was continuously increased. After the torque value reached 2.3 Nm, the reaction was terminated, and a PBT-PTMG copolymer was obtained.

[0095] Example 2

[0096] 18 parts by weight of terephthalic acid (PTA), 26 parts by weight of 1,4-butanediol (BG), and 56 parts by weight of polytetramethylene glycol (PTMG) (M n= 2000) and 100 ppm (based on Ti element) of Ti catalyst (tetrabutyl titanate, TBT) were added to a 2 L glass reactor, and the temperature was increased to 200°C over 1 hour while stirring under a nitrogen atmosphere. The molar ratio of BG / PTA was 3.0, and PTMG was used so that the content of polyether in the PBT-PTMG copolymer was 77 wt%.

[0097] A PBT-PTMG copolymer was prepared by performing the ES, PP, and PC steps in the same manner as in Example 1, except that the raw materials were used as described above.

[0098] At the end of the reaction, the conversion of esterification was 98%, and the torque was 2.0 Nm.

[0099] Example 3

[0100] A PBT-PTMG copolymer was prepared in the same manner as in Example 2, except that the molar ratio of BG / PTA was 2.6, and Ti catalyst was added in an amount of 50 ppm and 100 ppm before and after the ES reaction, respectively.

[0101] At the end of the reaction, the conversion of esterification was 98%, and the torque was 2.0 Nm.

[0102] Example 4

[0103] A PBT-PTMG copolymer was prepared in the same manner as in Example 2, except that the molar ratio of BG / PTA was 2.6, and Ti catalyst was added in an amount of 200 ppm before and after the ES reaction, and the PC reaction was performed for 2 hours.

[0104] At the end of the reaction, the conversion of esterification was 97%, and the torque was 2.6 Nm.

[0105] Example 5

[0106] A PBT-PTMG copolymer was prepared in the same manner as in Example 2, except that the molar ratio of BG / PTA was 2.6, Ti catalyst was added in an amount of 200 ppm before and after the ES reaction, and the PC reaction was performed at 245°C to 250°C for 2 hours and 30 minutes.

[0107] At the end of the reaction, the conversion of esterification was 97%, and the torque was 1.7 Nm.

[0108] Comparative Example 1

[0109] A PBT-PTMG copolymer was prepared in the same manner as in Example 3, except that Ti catalyst was added in an amount of 50 ppm only in the ES step.

[0110] At the end of the reaction, the conversion of esterification was 97%, as in Example 3, but the torque was as low as 1.0 Nm.

[0111] Comparative Example 2

[0112] A PBT-PTMG copolymer was prepared in the same manner as in Example 1, except that the molar ratio of BG / PTA was 2.6, and the Ti catalyst was added in an amount of 25 ppm in the ES step and 125 ppm in the PP step.

[0113] At the end of the reaction, the conversion of esterification was 97%, as in Example 1, but the torque was 1.9 Nm.

[0114] Comparative Example 3

[0115] A PBT-PTMG copolymer was prepared in the same manner as in Example 2, except that the molar ratio of BG / PTA was 2.6, and the Ti catalyst was added in an amount of 25 ppm in the ES step and 125 ppm in the PP step.

[0116] At the end of the reaction, the conversion of esterification was only 51%, and the torque was 0.5 Nm.

[0117] Comparative Example 4

[0118] A PBT-PTMG copolymer was prepared in the same manner as in Example 2, except that the molar ratio of BG / PTA was 2.5.

[0119] At the end of the reaction, the conversion of esterification was 93%, and the torque was 1.8 Nm.

[0120] Comparative Example 5

[0121] A PBT-PTMG copolymer was prepared in the same manner as in Example 5, except that the molar ratio of BG / PTA was 1.7, and the PC reaction was performed for 3 hours.

[0122] The conversion of esterification was 86%, and unlike Example 3, the torque did not increase further at 1.1 Nm.

[0123] Experimental Example

[0124] The PTMG content, intrinsic viscosity ([η]) at 25°C, and melt flow index (dg / min) of each PBT-PTMG copolymer prepared in the examples and comparative examples were measured by the following methods, and the results are shown in Table 1 below.

[0125] (1) Measurement method of PTMG content

[0126] About 10 mg to 20 mg of the copolymer was added to 1 ml of a mixed solution of chloroform-d and trifluoroacetic acid-d (ratio of 10:1), and stirred at room temperature until the copolymer was completely dissolved. The intrinsic viscosity ([η]) at 25°C was measured1 HNMR (500 MHz, Agilent) spectra were analyzed for PBT and PTMG content.

[0127] (2) Measurement method of intrinsic viscosity

[0128] After preparing polymer solutions of different concentrations (solvent: o-chlorophenol), the zero shear viscosity was measured to determine the intrinsic viscosity. The zero shear viscosity was determined by measuring the viscosity using a rotational rheometer DHR II [TA Instruments, USA] at a shear rate of 50 s -1

[0129] Polymer solutions were prepared at concentrations of 2 wt%, 1 wt%, 0.5 wt%, and 0.25 wt%. The specific viscosity (ηsp) was measured as a function of concentration (c), and was used to calculate the intrinsic viscosity according to the following mathematical equation 2.

[0130] [mathematical equation 2]

[0131]

[0132] (3) Measurement method of melt flow index

[0133] The samples were dehumidified and dried at 50°C for 24 hours, and their melt flow indices were measured according to ASTM D1238 (at a load of 2.16 kg at 230°C for 4 minutes).

[0134] (4) Measurement method of hardness

[0135] The Shore D hardness was measured according to ASTM D2240.

[0136] [table 1]

[0137]

[0138] Referring to Table 1, when the molar ratio of BG / PTA is greater than 2.5, and the catalyst is added in an amount of 50 ppm or more in the ES reaction and the PP reaction, respectively (Examples 1 to 5), the conversion rate of esterification is 97% or more, and the PBT-PTMG copolymer prepared has a high intrinsic viscosity of 2.2 or more at 25°C, and a melt flow index of 12 or less at a load of 2.16 kg at 230°C, despite the content of PTMG being 75 wt% or more.

[0139] However, when the catalyst is added to the ES reaction and the PP reaction without batching (Comparative Examples 1 and 2), the intrinsic viscosity is 1.9 or less, indicating that they do not satisfy the high viscosity performance.

[0140] ​Further, when the amount of catalyst added in the ES reaction and the PP reaction is less than 50 ppm, respectively (Comparative Example 3), or when the molar ratio of BG / PTA is 2.5 or less (Comparative Examples 4 and 5), the conversion of esterification is less than 95%, and all have an intrinsic viscosity of 2.0 or less, indicating that they do not satisfy the high viscosity performance.

[0141] From these results, it can be confirmed that, in order to prepare a poly(ether ester) copolymer having a high polyether content and having low hardness and high viscosity performance, the molar ratio of diol / dicarboxylic acid and the batch addition of catalyst must all be satisfied.

Claims

1. A method for producing a high viscosity poly(ether ester) copolymer having a polyether content of 60 to 90% by weight and an intrinsic viscosity at 25°C of 2.2 or more, and a melt flow index of 12 g / 10 min or less measured according to ASTM D1238, the method comprising: a) an esterification step of reacting a dihydric alcohol, a dicarboxylic acid and a polyether diol in the presence of a catalyst; b) a first polycondensation step of further adding a catalyst to the reaction mixture of step a) and conducting polycondensation under reduced pressure to produce a prepolymer; and c) a second polycondensation step of conducting polycondensation of the prepolymer under a pressure lower than the pressure of step b), wherein the molar ratio of dihydric alcohol / dicarboxylic acid added in step a) is 2.6 to 3, and the amount of catalyst added in step a) and step b) is 50 ppm or more, respectively, based on active metal. Step a) is conducted in a reactor equipped with a distillation column maintained at 80 to 150°C. Step a) is conducted at a temperature of 150 to 300°C and a pressure of 100 torr or more and less than 760 torr. Step b) is conducted at a temperature of 180 to 250°C and a pressure of more than 5 torr and 100 torr or less.

2. The method of making a high viscosity poly(ether ester) copolymer of claim 1, wherein, Step c) is conducted at a temperature of 180 to 250°C and a pressure of 5 torr or less.

3. The method of making a high viscosity poly(ether ester) copolymer of claim 1, wherein, The total amount of catalyst added in step a) and step b) is less than 500 ppm.

4. The method of making a high viscosity poly(ether ester) copolymer of claim 1, wherein, The number average molecular weight of the polyether diol is 500 to 3000 g / mol.

5. The method of making a high viscosity poly(ether ester) copolymer of claim 1, wherein, The poly(ether ester) copolymer has a Shore D hardness of 40 or less.

6. The method of making a high viscosity poly(ether ester) copolymer of claim 1, wherein, ​ 7. The method of making a high viscosity poly(ether ester) copolymer of claim 1, wherein, ​ 8. The method of making a high viscosity poly(ether ester) copolymer of claim 1, wherein, ​

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