Slurry composition of terephthalic acid and 1,4-butanediol, method for producing the same, and method for producing polybutylene terephthalate using the same.

Abstract

To provide a slurry composition containing terephthalic acid and 1,4-butanediol, wherein precipitation of terephthalic acid in the slurry composition is suppressed and a method for producing the slurry composition; and a method for producing polybutylene terephthalate with excellent reactivity in esterification reactions using this slurry composition.SOLUTION: There is provided a slurry composition containing terephthalic acid and 1,4-butanediol, wherein the terephthalic acid has a BET specific surface area of 1,500 cm2 / g or more, as measured by the krypton adsorption method, and is in the form of particles having a mean particle size D50 of 40 μm or more and 200 μm or less, determined by sieve analysis according to ASTM D1921-06 and calculated according to ISO 9276-2:2014. There is also provided a method for producing polybutylene terephthalate using this slurry composition.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a slurry composition containing terephthalic acid (hereinafter sometimes abbreviated as "TPA") and 1,4-butanediol (hereinafter sometimes abbreviated as "BDO"), and a method for producing the same. More specifically, the present invention relates to a slurry composition excellent in sedimentation resistance of terephthalic acid in the slurry composition and a method for producing the same. The present invention also relates to a method for producing polybutylene terephthalate (hereinafter sometimes abbreviated as "PBT") having excellent esterification reactivity using this slurry composition.

Background Art

[0002] Polybutylene terephthalate (PBT) using terephthalic acid (TPA) as the main component of the dicarboxylic acid component and 1,4-butanediol (BDO) as the main component of the diol component has excellent mechanical properties, heat resistance, moldability, and recyclability, and also has high mechanical strength and excellent chemical resistance. Therefore, it is widely used as a material for industrial molded products such as connectors, relays, and switches in automobiles and electric and electronic devices. PBT is further widely used in films, sheets, fibers (filaments), etc. Along with this, there is a demand for high-quality and highly productive PBT and a method for producing the same.

[0003] The production methods of PBT are roughly classified into a transesterification method using dimethyl terephthalate as a raw material for the dicarboxylic acid component and a direct polymerization method using terephthalic acid as a raw material. The transesterification method has a drawback that since the boiling points of methanol (boiling point 65°C) and tetrahydrofuran (hereinafter sometimes abbreviated as "THF") (boiling point 66°C), which are by-products of the reaction, are close, it is difficult to perform distillation separation after recovery. On the other hand, the direct polymerization method is attracting attention because it does not generate methanol and the raw material unit is also better than the transesterification method.

[0004] However, since terephthalic acid is insoluble in BDO, a dicarboxylic acid mainly composed of terephthalic acid used as a raw material for producing PBT by the direct polymerization method and a diol mainly composed of 1,4-butanediol are supplied in a slurry state. This slurry needs to be in a constantly stirred state or a fluid state to prevent the precipitation of terephthalic acid in the slurry. However, for example, when the stirring or fluid state of the slurry cannot be maintained due to equipment failure or the like, the terephthalic acid in the slurry will precipitate over time. When the precipitation of terephthalic acid is significant, even in a short time, high-intensity stirring and discharging are required to make it a uniform slurry again. In this case, if the stirring motor or circulation pump cannot handle it, continuous production cannot be continued.

[0005] Furthermore, in the production of polybutylene terephthalate by the direct polymerization method, the terephthalic acid in the raw material slurry does not melt and the esterification reaction proceeds in a solid-liquid state with BDO. That is, since the esterification reaction for producing polybutylene terephthalate is a solid-liquid reaction, the reaction rate is generally slow, and further improvement technologies are required. The reaction rate of the esterification reaction can be increased by raising the reaction temperature. However, in this case, the THF formation reaction of BDO will proceed simultaneously, and the amount of THF generated will be large, which is not practical.

[0006] For these reasons, in the production of PBT by the direct polymerization method, the development of technologies for suppressing the precipitation of terephthalic acid in the raw material slurry and enhancing the reactivity of the esterification reaction is desired.

[0007] Although Patent Document 1 and Patent Document 2 describe the specific surface area and particle size of terephthalic acid, there is no description regarding the sedimentation resistance of the slurry and the esterification reactivity. Moreover, both the specific surface area and particle size described in Patent Document 1 and Patent Document 2 are outside the scope of the present invention.

[0008] As mentioned above, in the direct polymerization method, one of the methods for producing PBT, PBT is produced using a dicarboxylic acid component mainly composed of terephthalic acid and a diol component mainly composed of BDO. Regarding the production of BDO, in recent years, in addition to conventional methods of producing BDO using fossil fuels such as petroleum as raw materials (referred to as "petrochemical-derived" in this invention), methods of producing BDO using biomass resources as raw materials (referred to as "biomass-derived" in this invention) have also been developed. For example, a method of obtaining BDO by hydrogenating succinic acid obtained by sugar fermentation (e.g., Patent Document 3) and a method of directly obtaining BDO by fermenting biomass resources such as sugar (e.g., Patent Document 4) are known. Furthermore, chemically recycled BDO produced by depolymerizing polybutylene terephthalate using a chemical recycling method has also been proposed (e.g., Patent Document 5).

[0009] Furthermore, regarding terephthalic acid, in recent years, methods have been developed to produce biomass-derived terephthalic acid using biomass resources as raw materials, in addition to conventional methods of producing petrochemical-derived terephthalic acid using fossil fuels such as petroleum as raw materials. For example, a method has been proposed to obtain isobutanol from a renewable carbon source and then obtain terephthalic acid by oxidation of paraxylene through dehydration dimerization of isobutanol (e.g., Patent Document 6). In addition, a method has been proposed to produce dimethyl terephthalate by depolymerizing polyethylene terephthalate using a chemical recycling method (e.g., Patent Documents 5, 7), and chemically recycled terephthalic acid can be produced by hydrolyzing the produced chemically recycled dimethyl terephthalate.

[0010] However, conventional methods do not involve the use of biomass-derived 1,4-butanediol or chemically recycled 1,4-butanediol, or biomass-derived terephthalic acid or chemically recycled terephthalic acid as slurries, nor do they address the challenges associated with raw material slurries used in the production of polybutylene terephthalate.

[0011] Furthermore, as mentioned above, in addition to petrochemical-derived BDO, biomass-derived BDO and chemically recycled BDO have been proposed in recent years as BDOs. However, conventional methods have not considered using compositions containing a diol component mainly composed of biomass-derived BDO or chemically recycled BDO and a dicarboxylic acid component mainly composed of terephthalic acid as PBT raw materials. Similarly, with respect to terephthalic acid, conventional methods have not considered the use of compositions containing a dicarboxylic acid component mainly composed of biomass-derived terephthalic acid or chemically recycled terephthalic acid, and a diol component mainly composed of 1,4-butanediol, as PBT raw materials. [Prior art documents] [Patent Documents]

[0012] [Patent Document 1] Japanese Patent Publication No. 2002-348261 [Patent Document 2] International Publication No. 2008 / 056801 [Patent Document 3] Japanese Patent Publication No. 2007-197654 [Patent Document 4] International Publication No. 2015 / 158716 [Patent Document 5] Japanese Patent Publication No. 2004-323378 [Patent Document 6] Special Publication No. 2013-506717 [Patent Document 7] Japanese Patent Publication No. 2001-151934 [Overview of the project] [Problems that the invention aims to solve]

[0013] The object of the present invention is to provide a slurry composition containing terephthalic acid and 1,4-butanediol, wherein the precipitation of terephthalic acid in the slurry composition is suppressed, a method for producing the same, and a method for producing polybutylene terephthalate with excellent reactivity in esterification reactions using this slurry composition. [Means for solving the problem]

[0014] The inventors of this invention have conducted extensive research to solve the above problems and have found a specific surface area and average particle size D 50 We discovered that this problem can be solved by using terephthalic acid, which has [a specific characteristic]. This invention was completed based on these findings, and its gist is as follows.

[0015] [1] A slurry composition comprising terephthalic acid and 1,4-butanediol, The terephthalic acid has a BET specific surface area of ​​1,500 cm² as measured by the krypton adsorption method. 2 The average particle size D is obtained by measuring by sieving in accordance with ASTM D1921-06 and calculating in accordance with ISO 9276-2:2014, with a value of 1 / g or more. 50 A slurry composition characterized by having particles of 40 μm or larger and 200 μm or smaller.

[0016] [2] The slurry composition according to [1], wherein the 1,4-butanediol is any of the following: 1,4-butanediol produced by direct fermentation of sugars, 1,4-butanediol produced by hydrogen reduction of succinic acid or succinic acid derivative produced using biomass resources, and 1,4-butanediol produced by depolymerization of polyester using 1,4-butanediol as a raw material.

[0017] [3] The slurry composition according to [1] or [2], wherein the terephthalic acid comprises either terephthalic acid produced by chemical recycling of polyester or terephthalic acid produced using biomass resources.

[0018] [4] A method for producing a slurry composition by mixing terephthalic acid and 1,4-butanediol, The terephthalic acid has a BET specific surface area of ​​1,500 cm² as measured by the krypton adsorption method. 2 The average particle size D is calculated according to ISO 9276-2:2014, and is measured by sieving in accordance with ASTM D1921-06. 50 A method for producing a slurry composition characterized by having particles of 40 μm or larger and 200 μm or smaller.

[0019] [5] A method for producing the slurry composition according to [4], wherein the 1,4-butanediol is any of the following: 1,4-butanediol produced by direct fermentation of sugar, 1,4-butanediol produced by hydrogen reduction of succinic acid or succinic acid derivative produced using biomass resources, and 1,4-butanediol produced by depolymerization of polyester using 1,4-butanediol as a raw material.

[0020] [6] A method for producing the slurry composition according to [4] or [5], wherein the terephthalic acid comprises either terephthalic acid produced by chemical recycling of polyester or terephthalic acid produced using biomass resources.

[0021] A method for producing polybutylene terephthalate using the slurry composition described in any of [7] [1] to [3].

[0022] A method for producing polybutylene terephthalate using a slurry composition produced by the method for producing a slurry composition described in any of [8] [4] to [6]. [Effects of the Invention]

[0023] The slurry composition of the present invention exhibits excellent resistance to sedimentation of terephthalic acid. Therefore, even if the stirring or flow state of the slurry composition cannot be maintained due to equipment failure or other circumstances, the sedimentation of terephthalic acid is suppressed, enabling stable production with excellent handling characteristics in the direct polymerization method for polybutylene terephthalate. Furthermore, because a uniform dispersion state of terephthalic acid and 1,4-butanediol can be stably maintained in the slurry composition, the esterification reaction rate is high when this is used as a raw material for polybutylene terephthalate, and the esterification reaction proceeds in a shorter time. In other words, polybutylene terephthalate can be produced more stably and in a shorter time, giving it very high industrial value. [Modes for carrying out the invention]

[0024] The present invention will be described in detail below, but the following descriptions of constituent elements are representative examples of embodiments of the present invention, and the present invention is not limited to these contents. In this invention, the "main component" in a dicarboxylic acid component refers to the component present in the component at a concentration of 50 mol% or more. The same applies to the "main component" in a diol component. Furthermore, "ppm" refers to "mass ppm".

[0025] [Slurry composition] The slurry composition of the present invention comprises terephthalic acid and 1,4-butanediol, wherein the terephthalic acid in the slurry composition has a BET specific surface area of ​​1,500 cm² as measured by the krypton adsorption method. 2 The average particle size D is obtained by measuring by sieving in accordance with ASTM D1921-06 and calculating in accordance with ISO 9276-2:2014, with a value of 1 / g or more. 50 (Hereafter simply referred to as "Average particle size D") 50 It is sometimes referred to as "[...]." It is characterized by having particle sizes of 40 μm or more and 200 μm or less.

[0026] In the present invention, the BET specific surface area and the average particle size D of terephthalic acid 50 refer to the BET specific surface area and the average particle size D of terephthalic acid before mixing it with 1,4-butanediol to form a slurry composition 50 However, this BET specific surface area and the average particle size D 50 are the same as the BET specific surface area and the average particle size D of terephthalic acid in the slurry composition 50 . That is, since terephthalic acid does not show solubility in 1,4-butanediol, there is no change in the form of terephthalic acid before and after mixing with 1,4-butanediol. Therefore, the BET specific surface area and the average particle size D of terephthalic acid before mixing it with 1,4-butanediol to form a slurry composition 50 are the same as the BET specific surface area and the average particle size D of terephthalic acid in the slurry composition 50 .

[0027] <Terephthalic acid> (Origin of terephthalic acid) The terephthalic acid used in the present invention (hereinafter sometimes referred to as "the terephthalic acid of the present invention" or "the TPA of the present invention") can be terephthalic acid synthesized by oxidation of paraxylene, a petrochemical product (terephthalic acid derived from petrochemicals), terephthalic acid derived from chemical recycling obtained by recovering waste polyester and depolymerizing the recovered polyester, or biomass-derived terephthalic acid obtained using paraxylene produced from isobutanol or ethanol produced from plants such as corn and sugarcane as raw materials The terephthalic acid of the present invention may be a mixture of two or more terephthalic acids having different origins. However, when mixing and using two or more terephthalic acids, the BET specific surface area and the average particle size D 50 are the measured values of terephthalic acid as a mixture From the perspective of aiming for a sustainable society for the global environment and future generations, the terephthalic acid of the present invention is preferably terephthalic acid derived from chemical recycling Also, from the same perspective, the terephthalic acid of the present invention is preferably biomass-derived terephthalic acid

[0028] (BET specific surface area of ​​terephthalic acid) The terephthalic acid of the present invention has a BET specific surface area of ​​1500 cm² as measured by the krypton gas adsorption method. 2 A minimum of / g is a mandatory requirement. This BET specific surface area is 1500 cm². 2 / g or more, preferably 1800cm 2 / g or more, more preferably 2000cm³ 2 / g or more, more preferably 2500cm² 2 It is 3500cm or more / g 2 It is most preferable that the BET specific surface area exceeds / g. On the other hand, the upper limit of the BET specific surface area of ​​terephthalic acid in the present invention is preferably 5000 cm². 2 / g or less, more preferably 4900cm² 2 / g or less, more preferably 4800cm² 2 It is less than / g. If the BET specific surface area of ​​terephthalic acid is below the lower limit of the above range, the sedimentation of terephthalic acid in the slurry composition will increase, and the esterification reaction rate will slow down, which is undesirable. If the BET specific surface area of ​​terephthalic acid is above the lower limit of the above range, the area in contact with BDO will increase, the resistance to sedimentation will increase, and the sedimentation will decrease. While a larger BET specific surface area of ​​terephthalic acid results in lower settling properties, it is difficult and impractical to produce terephthalic acid with a BET specific surface area exceeding the upper limit of the above range. If the BET specific surface area of ​​terephthalic acid is within the above range, the present invention exhibits excellent effects and practicality.

[0029] Terephthalic acid with a BET specific surface area within the above range can be obtained by adjusting the purification conditions in the terephthalic acid manufacturing process. Furthermore, the BET specific surface area can also be adjusted by crystallization of the purified terephthalic acid. For example, in a purification process in which terephthalic acid is heated and pressurized, mixed with water, and then filtered, using low temperature and strong stirring conditions can yield terephthalic acid with a large BET specific surface area. Conversely, using high temperature and weak stirring conditions can yield terephthalic acid with a small BET specific surface area. Furthermore, if the BET specific surface area of ​​the terephthalic acid subjected to purification is large, terephthalic acid with a large BET specific surface area can be obtained. Conversely, if the BET specific surface area of ​​the terephthalic acid subjected to purification is small, terephthalic acid with a small BET specific surface area can be obtained.

[0030] (Average particle size of terephthalic acid D 50 ) The terephthalic acid of the present invention has an average particle size of D 50 The minimum particle size must be 40 μm or larger. 50 The particle size is preferably 40 μm or larger, more preferably 45 μm or larger, more preferably 50 μm or larger, even more preferably 60 μm or larger, and most preferably 70 μm or larger, or 80 μm or larger. On the other hand, the average particle size D of the terephthalic acid of the present invention 50 The particle size is preferably 200 μm or less, more preferably 190 μm or less, even more preferably 180 μm or less, particularly preferably 170 μm or less, and most preferably 160 μm or less. Average particle size D of terephthalic acid 50 If the average particle size is below the lower limit of the above range, it is undesirable because it results in poor handling when treated as a powder. 50 If the average particle size D is above the lower limit, less terephthalic acid dust will be generated during handling when manufacturing the slurry, resulting in excellent handling properties. 50 When PBT is produced using terephthalic acid whose pH is above the lower limit mentioned above, the esterification reaction rate is high, which is preferable. On the other hand, the average particle size D of terephthalic acid 50 When the average particle size exceeds the upper limit of the above range, the terephthalic acid in the slurry composition tends to settle more easily, and from the viewpoint of the settling resistance of terephthalic acid, the average particle size D 50 Smaller is preferable.

[0031] Average particle size D 50 Terephthalic acid within the above range can be obtained by adjusting the purification conditions in the terephthalic acid manufacturing process. Furthermore, the average particle size D can also be obtained by crystallizing the purified terephthalic acid. 50 It can be adjusted. For example, in a purification operation in which terephthalic acid is mixed with water under heating and pressure and then filtered, by employing low temperature conditions and strong stirring conditions, the average particle size D 50 Terephthalic acid with a small particle size can be obtained. Conversely, by employing high temperature conditions and weak stirring conditions, the average particle size D can be reduced. 50 A large amount of terephthalic acid can be obtained. Furthermore, if the particle size of terephthalic acid subjected to purification is large, the average particle size D 50 Large terephthalic acid can be obtained, and conversely, if the particle size of the terephthalic acid subjected to purification is small, the average particle size D 50 A small amount of terephthalic acid can be obtained.

[0032] <1,4-butanediol> There are no particular restrictions on the method for producing 1,4-butanediol used in the slurry composition of the present invention. Common methods for producing BDO include the Reppe process, the allyl alcohol process, the butadiene process, and the hydrogenation of succinic acid. Furthermore, these intermediates or BDO itself may be produced by fermentation (direct fermentation).

[0033] From the perspective of aiming for a sustainable society for the sake of the global environment and future generations, biomass-derived BDO and chemically recycled BDO are preferred as the BDO used in this invention.

[0034] Biomass-derived 1,4-butanediol may be produced by direct fermentation of sugars, or by hydrogen reduction after producing succinic acid or succinic acid derivatives from biomass resources. Examples of succinic acid derivatives include succinic anhydride, succinic acid esters such as dialkyl succinates (more specifically, dialkyl succinates with an alkyl group having 1 to 4 carbon atoms, preferably 1 to 3, more preferably 1 to 2, and most preferably 1 carbon atom), etc. Furthermore, in any BDO manufacturing method, it is preferable to perform distillation purification or hydrogenation purification as needed at each step.

[0035] Furthermore, as an example of chemically recycled 1,4-butanediol, there is the chemically recycled 1,4-butanediol obtained by depolymerizing polybutylene terephthalate, as described in Patent Document 5.

[0036] In the present invention, 1,4-butanediol may be a mixture of two or more types of petrochemical-derived 1,4-butanediol, biomass-derived 1,4-butanediol, and chemically recycled 1,4-butanediol.

[0037] When using biomass-derived 1,4-butanediol as a raw material for the production of polybutylene terephthalate, it is preferable that the 1,4-butanediol in the composition of the present invention is also biomass-derived 1,4-butanediol. Furthermore, when using chemically recycled 1,4-butanediol as the raw material for the production of polybutylene terephthalate, it is preferable that the 1,4-butanediol in the composition of the present invention is also chemically recycled 1,4-butanediol.

[0038] <Ratio of terephthalic acid and BDO content> The ratio of terephthalic acid and BDO in the slurry composition of the present invention varies depending on the content of other copolymer components in the slurry composition, but from the viewpoint of using it as a raw material for the production of polybutylene terephthalate, it is preferable that the BOD is contained in the slurry composition of the present invention in such a ratio of 1.6 moles or more per mole of terephthalic acid, more preferably 1.7 moles or more, and even more preferably 1.8 moles or more. If this ratio is less than 1.6 moles, the viscosity of the slurry composition will increase and the fluidity of the slurry composition will deteriorate, which is undesirable. There is no particular upper limit to this ratio, but if this ratio is too high, the terephthalic acid in the slurry composition tends to settle easily, so it is preferable to have a ratio of 2.2 moles or less, particularly 2.0 moles or less, and especially preferably 1.9 moles or less. If the molar ratio of BDO to terephthalic acid is within the above range, the esterification reaction efficiency in the production process of polybutylene terephthalate is excellent and therefore preferable.

[0039] The slurry composition of the present invention may consist only of terephthalic acid and 1,4-butanediol, or it may contain dicarboxylic acid components other than terephthalic acid used in the production of PBT described later, diol components other than BDO, copolymer components other than these dicarboxylic acid components and diol components, polycondensation catalysts, etc. However, due to the effect of terephthalic acid's precipitation resistance and esterification reactivity improvement in the slurry composition of the present invention, the total content of terephthalic acid and BDO in the slurry composition of the present invention is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 97-100% by mass. In particular, the precipitation resistance of terephthalic acid is preferably evaluated for a slurry composition consisting of terephthalic acid and BDO.

[0040] <Method for producing slurry composition> The slurry composition of the present invention has the aforementioned BET specific surface area and average particle size D 50 The present invention can be produced by mixing terephthalic acid and BDO that satisfy the specified conditions and stirring until homogeneous. The upper limit of the temperature when preparing the slurry composition of the present invention is usually less than 100°C, preferably 90°C or less, more preferably 80°C or less, even more preferably 70°C or less, particularly preferably 65°C or less, and most preferably 60°C or less. On the other hand, the lower limit of this temperature is preferably 14°C or higher, particularly preferably 15°C or higher. The temperature of the slurry composition is preferably the same as the temperature at which the slurry was prepared.

[0041] [Method for producing polybutylene terephthalate] The method for producing polybutylene terephthalate of the present invention using the slurry composition of the present invention will be described below. In the following, polybutylene terephthalate produced by the method for producing polybutylene terephthalate of the present invention may be referred to as "polybutylene terephthalate of the present invention" or "PBT of the present invention".

[0042] <Raw material: Dicarboxylic acid component, diol component, copolymer component> In the present invention, PBT refers to a polymer having a structure in which terephthalic acid and 1,4-butanediol (BDO) components are ester-bonded, wherein 50 mol% or more of the dicarboxylic acid component consists of terephthalic acid, and 50 mol% or more of the diol component consists of BDO. The proportion of terephthalic acid in the total dicarboxylic acid component is preferably 70 mol% or more, more preferably 80 mol% or more, and particularly preferably 95 mol% or more. The proportion of BDO in the total diol component is preferably 70 mol% or more, more preferably 80 mol% or more, and even more preferably 95 mol% or more. If the amount of terephthalic acid or BDO is less than 50 mol%, the crystallization rate of PBT decreases, leading to a deterioration in moldability. In the method for producing polybutylene terephthalate according to the present invention, the slurry composition of the present invention is used as at least a portion of the raw material dicarboxylic acid component and raw material diol component.

[0043] In the present invention, the dicarboxylic acid component includes dicarboxylic acids and dicarboxylic acid derivatives. There are no particular restrictions on dicarboxylic acids other than terephthalic acid used as raw materials for PBT production. Examples include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 4,4'-benzophenonedicarboxylic acid, 4,4'-diphenoxyethanedicarboxylic acid, 4,4'-diphenylsulfondicarboxylic acid, and 2,6-naphthalenedicarboxylic acid; alicyclic dicarboxylic acids such as 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid; and aliphatic dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid. Examples of dicarboxylic acid derivatives include ester-forming derivatives of these dicarboxylic acids, such as esters and dicarboxylic acid halides. These dicarboxylic acid components other than terephthalic acid may be used individually or as a mixture of two or more. For dicarboxylic acid components such as succinic acid, those derived from chemical recycling or biomass may be used.

[0044] In the present invention, there are no particular restrictions on diol components other than BDO, and examples include aliphatic diols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,8-octanediol, and dibutylene glycol; alicyclic diols such as 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,1-cyclohexanedimethylol, and 1,4-cyclohexanedimethylol; and aromatic diols such as xylylene glycol, 4,4'-dihydroxybiphenyl, 2,2-bis(4-hydroxyphenyl)propane, and bis(4-hydroxyphenyl)sulfone. These diol components other than BDO may be used individually or in combination of two or more. For diol components other than BDO, biomass-derived or chemically recycled components may also be used.

[0045] In the present invention, further, hydroxycarboxylic acids such as lactic acid, glycolic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, 6-hydroxy-2-naphthalene carboxylic acid, p-β-hydroxyethoxybenzoic acid, alkoxycarboxylic acids, monofunctional components such as stearyl alcohol, benzyl alcohol, stearic acid, benzoic acid, t-butylbenzoic acid, benzoylbenzoic acid, trifunctional or higher polyfunctional components such as tricarballylic acid, trimellitic acid, trimesic acid, pyromellitic acid, gallic acid, trimethylolethane, trimethylolpropane, glycerol, pentaerythritol, etc., one or more of these can be used as copolymerization components.

[0046] <Method for Producing PBT> The method for producing PBT of the present invention can be carried out according to a conventional method except that the slurry composition of the present invention is used as at least a part of the dicarboxylic acid component and the diol component. For example, using the slurry composition of the present invention as a raw material slurry, heating the raw material slurry under normal pressure or reduced pressure to carry out an esterification reaction to obtain a PBT low polymer (oligomer), and then gradually reducing the pressure of the obtained oligomer while heating and carrying out a melt polycondensation reaction to obtain PBT through a melt polycondensation step.

[0047] As an example of the step of obtaining an oligomer, using a single esterification reaction tank or a multi-stage reaction apparatus in which a plurality of esterification reaction tanks are connected in series, while removing water and excess diol components generated in the reaction outside the system, the esterification reaction rate (the ratio of the carboxyl groups of the raw material dicarboxylic acid component that have reacted with the diol component and esterified) usually reaches 90% or more, and the esterification reaction is carried out under normal pressure or reduced pressure with or without using a catalyst to obtain an oligomer. Usually, the temperature of the esterification reaction is about 210 to 230 °C, the pressure is about 10 to 133 kPa, and the residence time is about 1 to 4 hours.

[0048] An example of a melt polycondensation process is a multi-stage reactor using a single melt polycondensation tank or multiple melt polycondensation tanks connected in series, for example, a fully mixed reactor with a stirring blade in the first stage, and horizontal plug-flow reactors with stirring blades in the second and third stages, in which the diol produced is distilled out of the system while heating under reduced pressure in the presence of a catalyst.

[0049] Typically, the polycondensation reaction is carried out at a temperature of 210-280°C, preferably around 220-250°C, and under reduced pressure of 27 kPa or less, preferably 13 kPa or less.

[0050] The reaction vessel may be a single vessel or a multi-stage vessel, but in order to suppress discoloration and deterioration and to suppress the increase of terminal groups such as vinyl groups, it is preferable to carry out the reaction in at least one reaction vessel under a high vacuum of usually 1.3 kPa or less, preferably 0.3 kPa or less. To increase the reaction rate, conditions such as increasing the degree of reduced pressure, increasing the heating rate, and increasing the rate at which the reaction liquid level is renewed can be adopted.

[0051] The PBT obtained by the polycondensation reaction is usually extracted in strand or sheet form through an outlet at the bottom of the polycondensation reaction vessel, and then cut with a cutter while or after water cooling to form granular material such as pellets or chips (for example, about 3 to 10 mm in length).

[0052] <Polycondensation catalyst> When polycondensing oligomers obtained by the esterification reaction of a diol component and a dicarboxylic acid component, a titanium compound and preferably a Group 2A metal compound of the periodic table are typically used as catalysts. These catalyst components may be used in the esterification reaction and then proceed directly to the polycondensation reaction, or they may not be used in the esterification reaction, or only the titanium catalyst may be used, with the remaining catalyst components added at the polycondensation stage. Furthermore, a portion of the final amount of catalyst to be used may be used in the esterification reaction, and additional catalysts may be added as appropriate as the polycondensation reaction progresses. In any case, in this invention, the final PBT will inevitably contain titanium and preferably a metal from Group 2A of the periodic table, the amount of which will be described later.

[0053] Specific examples of titanium compounds include inorganic titanium compounds such as titanium dioxide and titanium tetrachloride, titanium alcoholates such as tetramethyl titanate, tetraisopropyl titanate, and tetrabutyl titanate, and titanium phenolates such as tetraphenyl titanate. These may be used individually or in combination of two or more. Among these, tetraalkyl titanate is preferred, and among those, tetrabutyl titanate is preferred.

[0054] The titanium catalyst content in the PBT of the present invention is preferably 5 to 100 ppm by mass ratio of titanium atoms to PBT. More preferably 10 ppm or more, even more preferably 20 ppm or more, and most preferably 25 ppm or more. Furthermore, more preferably 90 ppm or less, even more preferably 80 ppm or less, particularly preferably 60 ppm or less, especially preferably 50 ppm or less, and most preferably 40 ppm or less. If the titanium content is too high, the color, hydrolysis resistance, and solution haze will deteriorate, and the resulting molded product will exhibit increased fisheye. If the titanium content is too low, the polymerization properties will deteriorate.

[0055] Specific examples of Group 2A metal compounds in the present invention include various compounds of beryllium, magnesium, calcium, strontium, and barium. However, magnesium compounds and / or calcium compounds are preferred in terms of ease of handling and availability, as well as catalytic effect, and magnesium compounds, which exhibit excellent catalytic effect, are particularly preferred. Specific examples of magnesium compounds include magnesium acetate, magnesium hydroxide, magnesium carbonate, magnesium oxide, magnesium alkoxide, and magnesium hydrogen phosphate. Specific examples of calcium compounds include calcium acetate, calcium hydroxide, calcium carbonate, calcium oxide, calcium alkoxide, and calcium hydrogen phosphate. These Group 2A metal compounds of the periodic table may be used alone or in combination of two or more. Among these, magnesium acetate is preferred.

[0056] The content of the Group 2A metal in the PBT of the present invention is not particularly limited, but the mass ratio of the Group 2A metal atom to PBT is preferably 3 to 150 ppm. This amount is more preferably 5 ppm or more, still more preferably 10 ppm or more. Also, this amount is more preferably 50 ppm or less, still more preferably 40 ppm or less, particularly preferably 30 ppm or less, and most preferably 15 ppm or less. When the content of the Group 2A metal is too high, the color tone, hydrolysis resistance, etc. deteriorate, and when it is too low, the polymerization property deteriorates. When using an acetate of a Group 2A metal, since the acetic acid source enters the reaction system, the amount of the Group 2A metal in PBT is preferably 15 ppm or less.

[0057] The molar ratio of the titanium atom to the Group 2A metal atom (Group 2A metal / titanium) contained in the PBT of the present invention is usually 0.01 to 100, preferably 0.1 to 10, more preferably 0.3 to 3, and still more preferably 0.3 to 1.5.

[0058] The metal content such as titanium atoms in PBT can be measured using methods such as atomic emission, atomic absorption, Inductively Coupled Plasma (ICP), etc. after recovering the metal in the polymer by methods such as wet ashing.

[0059] In the production of the PBT of the present invention, separate from the above-mentioned titanium compounds and Group 2A metal compounds, antimony compounds such as antimony trioxide, germanium compounds such as germanium dioxide and germanium tetroxide, manganese compounds, zinc compounds, zirconium compounds, cobalt compounds, phosphoric acid, phosphorous acid, hypophosphorous acid, polyphosphoric acid, phosphorus compounds such as their esters and metal salts, reaction aids such as sodium hydroxide and sodium benzoate may be used.

[0060] <Physical properties of PBT> When the PBT of the present invention is used in compounding and injection molding, the intrinsic viscosity of the PBT is preferably 0.6 to 1.3 dL / g. If the intrinsic viscosity is less than 0.6 dL / g, the mechanical strength of the molded product will be insufficient, and if it exceeds 1.3 dL / g, the melt viscosity will be high, fluidity will deteriorate, and moldability will tend to worsen. The intrinsic viscosity of the PBT of the present invention is more preferably 0.65 to 1.26 dL / g, and even more preferably 0.7 to 1.2 dL / g.

[0061] Furthermore, when the PBT pellets of the present invention are used for extrusion applications of films, sheets, or filaments, the intrinsic viscosity of PBT is typically 1.00 to 1.60 dL / g, preferably 1.03 to 1.50 dL / g, more preferably 1.05 to 1.55 dL / g, even more preferably 1.10 to 1.50 dL / g, and particularly preferably 1.15 to 1.35 dL / g. If the intrinsic viscosity is less than 1.00 dL / g, the extrusion moldability deteriorates, leading to resin drawdown and molding losses, resulting in insufficient mechanical strength of extruded products such as films, or the melt viscosity becomes low, resulting in excessive fluidity and poor extrusion moldability. On the other hand, if the intrinsic viscosity exceeds 1.60 dL / g, the melt viscosity becomes high, fluidity deteriorates, and extrusion moldability tends to worsen.

[0062] The intrinsic viscosity of PBT can be determined by the method described in the Examples section below. [Examples]

[0063] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way to the following examples unless it exceeds the gist of the invention. The measurement methods for the physical properties and evaluation items used in the following examples are as follows:

[0064] (1) BET specific surface area of ​​terephthalic acid Terephthalic acid particles subjected to reduced-pressure heat treatment at 150°C under vacuum for 2 hours were subjected to adsorption isotherms (adsorbed gas: krypton) measured at liquid nitrogen temperature. The specific surface area was calculated using BET multipoint analysis with the obtained adsorption isotherms. The adsorption cross-section of krypton was assumed to be 0.205 nm. 2 This was the analysis.

[0065] (2) Average particle size D of terephthalic acid 50 The values ​​were measured using the sieving method in accordance with ASTM D1921-06 and calculated in accordance with ISO 9276-2:2014.

[0066] (3) Precipitation of terephthalic acid A slurry was prepared by mixing 1.00 mole of terephthalic acid with 1.80 moles of BDO, and the mixture was stirred until it was sufficiently homogeneous. This slurry was placed in a 1000 mL graduated cylinder and left at 60°C for 1 hour. The ratio of the supernatant liquid (the ratio of the supernatant liquid portion to the total volume) after 1 hour was measured. The smaller this ratio, the better the terephthalic acid's resistance to settling. In other words, it is a slurry with excellent handling properties. This value is preferably 10% or less.

[0067] (4) Intrinsic viscosity of PBT (IV) The following procedure was used to determine the viscosity using an Ubbelohde viscometer. Using a phenol / tetrachloroethane mixed solvent (mass ratio 1 / 1), the number of seconds for dropping a 1.0 g / dL polymer solution and the solvent alone was measured at 30°C and calculated using the following formula. IV = ((1 + 4K H η sp ) 0.5 -1) / (2K H ·C) (However, η sp =η0-1, where η is the number of seconds the polymer solution falls, η0 is the number of seconds the solvent falls, C is the polymer solution concentration (g / dL), and K H (This is Huggins' constant, and we adopted 0.33.)

[0068] (5) Concentrations of titanium and Group 2A metals in PBT PBT was wet-decomposed using high-purity sulfuric acid and nitric acid for the electronics industry, and measured using a high-resolution ICP (Inductively Coupled Plasma)-MS (Mass Spectrometer) (Thermoquest).

[0069] [BET specific surface area and average particle size D of terephthalic acid derived from petrochemicals] 50 [Adjustment] In the following examples and comparative examples, commercially available high-purity terephthalic acid (PTA) (PT Mitsubishi Chemical Indonesia, high-purity terephthalic acid), which is produced by oxidizing p-xylene derived from petrochemicals in an acetic acid solvent in the presence of a catalyst containing cobalt and manganese, and then purifying it by hydrogenation, or commercially available medium-purity terephthalic acid (QTA) that has not undergone hydrogenation, is used as the terephthalic acid, and the following treatments are performed to obtain the BET specific surface area and average particle size D 50 A modified version was used. Commercially available high-purity terephthalic acid (PTA) or medium-purity terephthalic acid (QTA) and water were placed in an autoclave and stirred under nitrogen pressure. Stirring was performed for 1 m 3 The process was carried out under stirring conditions of approximately 0.5 to 5 horsepower per unit area and a linear velocity of the impeller of approximately 0.5 to 5 m / s. The mixture was then treated at an arbitrary temperature of 150 to 250°C for several hours, filtered at the treatment temperature, and then cooled to room temperature to extract terephthalic acid. By changing the temperature, time, and stirring conditions, various BET specific surface areas and average particle size D can be obtained. 50 Terephthalic acid was obtained. In this purification process, the BET specific surface area tends to increase with lower temperatures and decrease with higher temperatures. The BET specific surface area also tends to increase with stronger stirring conditions, such as higher stirring horsepower and linear stirring velocity. Furthermore, even under the same conditions, a larger surface area of ​​the treated terephthalic acid results in terephthalic acid with a larger BET specific surface area, while a smaller surface area results in terephthalic acid with a smaller BET specific surface area. Average particle size D 50Regarding this, the average particle size tends to decrease as the processing temperature decreases and increases as the processing temperature decreases. The stirring conditions, specifically the stirring horsepower and stirring linear velocity, are related to the average particle size D. 50 The average particle size D tends to decrease. Also, even when treated under the same conditions, if the particle size of the terephthalic acid to be treated is large, the average particle size D 50 When the particle size of the terephthalic acid to be treated is small, the average particle size D 50 This results in small terephthalic acid.

[0070] In this way, various BET specific surface areas and average particle size D 50 We obtained terephthalic acid derived from petrochemicals. The BET specific surface area and average particle size D obtained from the above process 50 Different petrochemical-derived terephthalic acid was used individually, or treated terephthalic acid and untreated terephthalic acid were appropriately blended, and the BET specific surface area and average particle size D for each example and comparative example are shown in Tables 1-3. 50 Terephthalic acid derived from petrochemicals was prepared and used.

[0071] [Production of biomass-derived 1,4-butanediol] <Production Example 1: 1,4-Butanediol produced by hydrogenation of biomass-derived succinate ester> BDO manufactured by Yuanli Chemical Group and BDO manufactured by Zhejiang Boju New Materials Co., Ltd. were mixed to obtain a mixture. The resulting mixture was subjected to vacuum distillation, and the primary, main, and secondary fractions were obtained in the order of distillation. A portion of the obtained main fraction was extracted and analyzed by gas chromatography, and the 1,4-butaneziel content was found to be 99% by mass or more.

[0072] [Chemical Recycling: Production of 1,4-Butanediol] <Production Example 2: 1,4-butanediol produced by depolymerization of PBT> Chemical recycled BDO was manufactured in accordance with Example 3 of Japanese Patent Publication No. 2004-323378. 1030 parts by mass of polybutylene terephthalate, 3200 parts by mass of methanol, and 13 parts by mass of sodium carbonate were supplied to an autoclave equipped with a stirring blade. The autoclave was immersed in an oil bath at 200°C and the reaction was carried out with stirring at a pressure of 1.3 MPa for 8 hours. The autoclave was removed from the oil bath and cooled to below 10°C in ice water to obtain a slurry. The obtained slurry was separated into solid and liquid components using filter paper to obtain a filtrate. The obtained filtrate was placed in a distillation apparatus equipped with a thermometer, vacuum control device, stirring blade, condenser, and fraction receiver. After recovering methanol and tetrahydrofuran as the initial fraction, vacuum distillation was performed to obtain the primary fraction, main fraction, and secondary fraction in the order of distillation. A portion of the obtained main fraction was extracted and analyzed by gas chromatography, revealing that the 1,4-butanediol content was 99% by mass or more.

[0073] [Chemical recycling of terephthalic acid production and BET specific surface area and average particle size D 50 [Adjustment] <Manufacturing Example 3: Production of Chemically Recycled Terephthalic Acid 1 and BET Specific Surface Area and Average Particle Size D 50 Adjustment > Referencing the method described in Japanese Patent Publication No. 2001-151934, chemically recycled dimethyl terephthalate 1 was obtained as follows. A flask equipped with a fraction recovery receiver, a stirrer, and a thermometer contained 100 parts by mass of waste fiber made of polyethylene terephthalate, 100 parts by mass of ethylene glycol, and 1.5 parts by mass of sodium carbonate. This flask was immersed in an oil bath at 210°C and reacted for 10 hours while removing the light-boiling components to obtain depolymerization reaction solution 1. The obtained depolymerization reaction solution 1 was filtered hot through a glass filter to obtain filtrate 1. To the obtained filtrate 1, 200 parts by mass of methanol and 0.5 parts by mass of sodium carbonate were added and reacted at 65°C for 1 hour to obtain reaction solution 2. The obtained reaction solution 2 was placed in a vacuum distillation apparatus equipped with a fraction recovery receiver, Liebig condenser, stirrer, thermometer, and pressure controller. The distillation apparatus was immersed in an oil bath, and the temperature and pressure of the oil bath were controlled while observing the distillate. The initial fraction, main fraction, and stock residue were obtained in the order of distillation. The obtained main fraction and xylene were placed in a round-bottom flask, heated to a homogeneous solution, and then cooled to room temperature for crystallization to obtain a slurry. The obtained slurry was filtered through a glass filter to obtain a cake. The obtained cake was placed in a round-bottom flask and attached to an evaporator equipped with an oil bath. Xylene was removed from the cake under reduced pressure to obtain a white solid (chemically recycled dimethyl terephthalate 1). A portion of the obtained white solid was extracted and analyzed by gas chromatography, and the dimethyl terephthalate content was found to be 99% by mass or more.

[0074] The obtained white solid dimethyl terephthalate 1 was dissolved in methylene chloride, and a methanol solution of potassium hydroxide was added to hydrolyze it to obtain reaction solution 1. 60% by mass of sulfuric acid was added to the obtained reaction solution 1 to neutralize it and obtain slurry 2. Slurry 2 was filtered using a centrifuge to obtain cake 2. Cake 2 was supplied to pure water and mixed to obtain slurry 3. Slurry 3 was filtered using a centrifuge to obtain cake 3. Cake 3 was again supplied to pure water and mixed to obtain slurry 4. Slurry 4 was filtered using a centrifuge to obtain cake 4. Cake 4 was placed in a round-bottom flask, attached to an evaporator equipped with an oil bath, and light-boiling components were removed from cake 4 under reduced pressure to obtain chemically recycled terephthalic acid 1 as a white solid. Analysis of a portion of the obtained white solid by liquid chromatography revealed that the terephthalic acid content was 99% by mass or more. The obtained chemically recycled terephthalic acid 1 white solid was crystallized, resulting in a BET specific surface area of ​​2050 cm². 2 / g, average particle size D 50 Chemically recycled terephthalic acid 1 with a size of 132 μm was obtained.

[0075] <Manufacturing Example 4: Chemical Recycling of Terephthalic Acid 2 and BET Specific Surface Area and Average Particle Size D 50 Adjustment > Referencing the method described in Japanese Patent Publication No. 2004-323378, chemically recycled dimethyl terephthalate 2 was obtained as follows. In an autoclave equipped with a stirrer and thermometer, 100 parts by mass of waste polyethylene terephthalate fiber, 300 parts by mass of methanol, and 1.5 parts by mass of sodium carbonate were placed. This autoclave was immersed in an oil bath at 150°C and reacted at 1.3 MPa for 10 hours. After that, a distillation tube was attached to the autoclave, and the pressure was slowly reduced to atmospheric pressure to distill off the light-boiling components to obtain depolymerization reaction solution 1. After lowering the temperature of the obtained depolymerization reaction solution 1 to room temperature, xylene was added and the mixture was immersed in an oil bath at 120°C to obtain slurry 1. The obtained slurry 1 was filtered through a glass filter, cooled to room temperature, and crystallized to obtain slurry 2. The obtained slurry 2 was separated into solid and liquid components using a centrifuge to obtain cake 2. The obtained cake 2 was placed in a flask equipped with a fraction recovery receiver, stirrer, and thermometer, and then immersed in an oil bath. While monitoring the distillate, the temperature and pressure of the oil bath were controlled, and the initial fraction, main fraction, and residue were obtained in the order of distillation. A portion of the obtained main fraction was extracted and analyzed by gas chromatography, and the dimethyl terephthalate content was found to be 99% by mass or more. Using the main fraction of dimethyl terephthalate (chemically recycled dimethyl terephthalate 2) instead of dimethyl terephthalate 1, hydrolysis and purification were carried out in the same manner as in Production Example 3 to obtain chemically recycled terephthalate 2, a white solid with a terephthalic acid content of 99% by mass or more. The obtained chemically recycled terephthalic acid 2 white solid was crystallized, resulting in a BET specific surface area of ​​2080 cm². 2 / g, average particle size D 50 Chemically recycled terephthalic acid 2 with a particle size of 131 μm was obtained.

[0076] <Manufacturing Example 5: Manufacturing of chemically recycled terephthalic acid 3 and BET specific surface area and average particle size D 50 Adjustment > Referencing the method described in Japanese Patent Publication No. 2001-151934, chemically recycled dimethyl terephthalate 3 was obtained as follows. 100 parts by mass of polybutylene terephthalate containing glass filler and 200 parts by mass of methanol were placed in an autoclave equipped with a stirrer and thermometer. This autoclave was immersed in an oil bath at 170°C and reacted at 5.5 MPa for 5 hours. After that, the autoclave was removed from the oil bath and allowed to cool to room temperature to obtain depolymerization reaction solution 1. The obtained depolymerization reaction solution 1 was filtered through a glass filter to obtain the solids. Tetrahydrofuran was added to the obtained solids to dissolve the white solids contained in the solids, and the glass filler was removed as a filtrate by filtration to obtain solution 1. The obtained solution 1 was placed in a flask equipped with a fraction recovery receiver, stirrer and thermometer, and then immersed in an oil bath. While observing the distillate, the temperature and pressure of the oil bath were controlled, and the light-boiling component containing tetrahydrofuran, the initial distillate, the main distillate, and the residue were obtained in the order of distillation. A portion of the obtained main distillate was extracted and analyzed by gas chromatography, and the dimethyl terephthalate content was found to be 99% by mass or more. Using the main fraction of dimethyl terephthalate (chemically recycled dimethyl terephthalate 3) instead of dimethyl terephthalate 1, hydrolysis and purification were carried out in the same manner as in Production Example 3 to obtain chemically recycled terephthalate 3, a white solid with a terephthalic acid content of 99% by mass or more. The obtained chemically recycled terephthalic acid 3 white solid was crystallized to obtain a BET specific surface area of ​​2060 cm². 2 / g, average particle size D 50 Chemically recycled terephthalic acid 3 with a particle size of 133 μm was obtained.

[0077] The BET specific surface area and average particle size D of terephthalic acid from different sources used in each example and comparative example shown in Tables 1-3 below are also shown. 50 From the values, the BET specific surface area and average particle size D of terephthalic acid can be determined. 50 There is no correlation between the two, and a large BET specific surface area does not necessarily mean that the average particle size D 50 It cannot be said that it is small, and a small BET specific surface area does not necessarily mean that the average particle size D50 It cannot be said that it is large, BET specific surface area and average particle size D 50 It can be seen that this is an independent physical property.

[0078] [Example 1] PBT was manufactured according to the following procedure.

[0079] Table 1 shows the BET specific surface area and average particle size D 50 1.00 mole of petrochemical-derived terephthalic acid was mixed with 1.80 moles of petroleum-derived BDO (manufactured by Mitsubishi Chemical Corporation) and thoroughly stirred at 60°C until homogeneous. When the settling properties of the terephthalic acid in this slurry were evaluated, the proportion of the supernatant liquid portion after standing at 60°C for 1 hour was 5%. This slurry was continuously supplied to an esterification reactor equipped with a screw-type stirrer packed with PBT oligomers with an esterification rate of 99%, and the esterification reaction was carried out. A BDO solution containing tetrabutyl titanate catalyst in an amount of 40 ppm titanium relative to PBT was supplied to the esterification reactor. Additional BDO was supplied to the esterification reactor so that the molar ratio of BDO to terephthalic acid was 3.2. The temperature of the reactor was 226°C, the pressure was 60 kPa, and the average residence time until an esterification rate of 96.5% was reached was 150 minutes.

[0080] Next, the PBT oligomer with an esterification rate of 96.5% was continuously transferred to the first polycondensation reactor. In the first polycondensation reactor, the polycondensation reaction was carried out continuously in the presence of a magnesium acetate tetrahydrate catalyst in an amount of 10 ppm relative to PBT. The reaction temperature was 230°C, the pressure was 3.9 kPa, and the average residence time was 120 minutes. The product was then transferred to the second polycondensation reactor, where the polycondensation reaction was carried out continuously. The reaction temperature was 240°C, the pressure was 130 Pa, and the average residence time was 80 minutes.

[0081] The obtained polymer was extracted via an extraction gear pump through an extraction line, filtered, and continuously extracted in strand form from a die head. It was then cut with a rotary cutter to obtain PBT pellets (approximately 3 mm in major diameter, 2 mm in minor diameter, and 4 mm in length). The intrinsic viscosity (IV) of the obtained PBT was 0.85 dL / g. The results are summarized in Table 1.

[0082] [Examples 2-15, Comparative Examples 1-5] In Example 1, the raw material terephthalic acid was selected, and the BET specific surface area and average particle size D shown in Tables 1-3 were used. 50 Using terephthalic acid derived from each of the descriptions, and using BDO derived from each of the descriptions, PBT was obtained in the same manner as in Example 1, except for the conditions shown in Tables 1 to 3, and evaluated in the same manner, and the results are shown in Tables 1 to 3. In Tables 1-3, "chemical recycling" is abbreviated as "CR," "petrification-derived" as "petrification," and "biomass-derived" as "bio." Therefore, "chemically recycled terephthalic acid 1" obtained in Production Example 3 is written as "CRTPA1," "chemically recycled terephthalic acid 1" obtained in Production Example 4 is written as "CRTPA2," and "chemically recycled terephthalic acid" obtained in Production Example 5 is written as "CRTPA3."

[0083] [Table 1]

[0084] [Table 2]

[0085] [Table 3]

[0086] As shown in Tables 1 and 2, the slurry compositions of Examples 1 to 15 that satisfy the requirements of the present invention exhibit excellent resistance to terephthalic acid settling and also have excellent esterification reactivity (short average residence time in the esterification tank). Furthermore, this effect can be obtained not only when using petroleum-derived terephthalic acid, but also when using chemically recycled terephthalic acid. Similarly, the same effect can be obtained when using biomass-derived BDO or chemically recycled BDO, not just petroleum-derived BDO. In contrast, the slurry compositions of Comparative Examples 1 to 5 in Table 3, which did not satisfy the requirements of the present invention, showed inferior resistance to terephthalic acid settling and esterification reactivity.

Claims

1. A slurry composition containing terephthalic acid and 1,4-butanediol, The terephthalic acid has a BET specific surface area of ​​1,500 cm² as measured by the krypton adsorption method. ２ The average particle size D was obtained by measuring by sieving in accordance with ASTM D1921-06 and calculating in accordance with ISO 9276-2:2014, with a particle size of 1 / g or more. ５０ A slurry composition characterized by having particles of 40 μm or more and 200 μm or less in size.

2. The slurry composition according to claim 1, wherein the 1,4-butanediol comprises any of the following: 1,4-butanediol produced by direct fermentation of sugars; 1,4-butanediol produced by hydrogen reduction of succinic acid or succinic acid derivative produced using biomass resources; and 1,4-butanediol produced by depolymerization of polyester using 1,4-butanediol as a raw material.

3. The slurry composition according to claim 1, wherein the terephthalic acid comprises either terephthalic acid produced by chemical recycling of polyester or terephthalic acid produced using biomass resources.

4. A method for producing a slurry composition by mixing terephthalic acid and 1,4-butanediol, The terephthalic acid has a BET specific surface area of ​​1,500 cm² as measured by the krypton adsorption method. ２ The average particle size D was obtained by measuring by sieving in accordance with ASTM D1921-06 and calculating in accordance with ISO 9276-2:2014, with a value of 1 / g or more. ５０ A method for producing a slurry composition, characterized in that the particles are 40 μm or larger and 200 μm or smaller.

5. A method for producing a slurry composition according to claim 4, wherein the 1,4-butanediol comprises any of the following: 1,4-butanediol produced by direct fermentation of sugars, 1,4-butanediol produced by hydrogen reduction of succinic acid or succinic acid derivative produced using biomass resources, and 1,4-butanediol produced by depolymerization of polyester using 1,4-butanediol as a raw material.

6. A method for producing the slurry composition according to claim 4, wherein the terephthalic acid comprises either terephthalic acid produced by chemical recycling of polyester or terephthalic acid produced using biomass resources.

7. A method for producing polybutylene terephthalate using the slurry composition described in any one of claims 1 to 3.

8. A method for producing polybutylene terephthalate using a slurry composition produced by the method for producing a slurry composition described in any one of claims 4 to 6.

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