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

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 to a slurry composition that exhibits excellent resistance to sedimentation 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") that exhibits excellent esterification reactivity using the slurry composition. [Background technology]

[0002] Polybutylene terephthalate (PBT), which uses terephthalic acid (TPA) as the main dicarboxylic acid component and 1,4-butanediol (BDO) as the main diol component, has excellent mechanical properties, heat resistance, moldability, and recyclability. Because of its high mechanical strength and excellent chemical resistance, it is widely used as a material for industrial molded products such as connectors, relays, and switches in automobiles and electrical and electronic devices. PBT is also widely used in films, sheets, fibers (filaments), and other applications. Consequently, there is a demand for high-quality PBT with excellent productivity and for its production methods.

[0003] PBT manufacturing methods are broadly divided into the transesterification method, which uses dimethyl terephthalate as the dicarboxylic acid component, and the direct polymerization method, which uses terephthalic acid as the raw material. The transesterification method has the disadvantage that the boiling points of the by-products generated in the reaction, methanol (boiling point 65°C) and tetrahydrofuran (hereinafter sometimes abbreviated as "THF") (boiling point 66°C), are close to each other, making it difficult to separate them by distillation after recovery. On the other hand, the direct polymerization method is attracting attention because it does not generate methanol and has a better raw material consumption rate than the transesterification method.

[0004] However, because terephthalic acid does not dissolve in BDO, the dicarboxylic acid containing terephthalic acid as the main component and the diol containing 1,4-butanediol as the main component used as raw materials for the production of PBT by the direct polymerization method are supplied in the form of a slurry, which must be constantly stirred or fluidized to prevent the terephthalic acid from settling in the slurry. However, if the stirring and fluidization of the slurry cannot be maintained due to, for example, equipment failure, the terephthalic acid in the slurry will settle over time. If the settling of terephthalic acid is significant, even in a short period of time, high-intensity stirring and discharge are required to make the slurry uniform again. In this case, if the stirring motor or circulation pump cannot cope with the situation, continuous production cannot be continued.

[0005] Furthermore, when producing polybutylene terephthalate by the direct polymerization method, the terephthalic acid in the raw material slurry does not melt, but the esterification reaction with BDO proceeds in a solid-liquid state. In other words, since the esterification reaction for producing polybutylene terephthalate is a solid-liquid reaction, the reaction rate is generally slow, and further improvement techniques are needed. The reaction rate of the esterification reaction can be increased by increasing the reaction temperature, but in this case, the reaction of converting BDO to THF proceeds simultaneously, resulting in a large amount of THF produced, which is not practical.

[0006] For these reasons, in the production of PBT by the direct polymerization method, it is desirable to develop a technology that can suppress the precipitation of terephthalic acid in the raw material slurry and increase the reactivity of the esterification reaction.

[0007] Although Patent Documents 1 and 2 describe the specific surface area and particle size of terephthalic acid, they do not describe the settling resistance or esterification reactivity of the slurry. Furthermore, the specific surface areas and particle sizes described in Patent Documents 1 and 2 are both outside the scope of the present invention.

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

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

[0010] However, in conventional methods, no consideration has been given to using biomass-derived 1,4-butanediol, chemically recycled 1,4-butanediol, or biomass-derived terephthalic acid or chemically recycled terephthalic acid as a slurry, nor to issues associated with the raw material slurry when producing polybutylene terephthalate using the raw material slurry that uses biomass-derived 1,4-butanediol, chemically recycled 1,4-butanediol, or biomass-derived terephthalic acid or chemically recycled terephthalic acid.

[0011] As mentioned above, in addition to petrochemical-derived BDO, biomass-derived BDO and chemically recycled BDO have been proposed in recent years. However, in conventional methods, the use of a composition containing a diol component primarily composed of biomass-derived BDO or chemically recycled BDO and a dicarboxylic acid component primarily composed of terephthalic acid as a PBT raw material has not been investigated. Similarly, with regard to terephthalic acid, in conventional methods, there has been no consideration of using a composition 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 a PBT raw material. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-348261 [Patent Document 2] International Publication No. 2008 / 056801 [Patent Document 3] Japanese Patent Application Laid-Open No. 2007-197654 [Patent Document 4] International Publication No. 2015 / 158716 [Patent Document 5] Japanese Patent Application Laid-Open No. 2004-323378 [Patent Document 6] Special Publication No. 2013-506717 [Patent Document 7] Japanese Patent Application Laid-Open No. 2001-151934 Summary of the Invention [Problem to be solved by the invention]

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

[0014] As a result of extensive research to solve the above problems, the present inventors have found that a specific surface area and average particle size D 50 It has been found that this problem can be solved by using terephthalic acid having the formula: The present invention was completed based on these findings, and the gist of the present invention 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 cm as measured by the krypton adsorption method. 2 / g or more, and the average particle size D is measured by the sieve method in accordance with ASTM D1921-06 and calculated in accordance with ISO 9276-2:2014. 50 A slurry composition characterized in that the particles are in the form of particles of 40 μm or more and 200 μm or less.

[0016] [2] The slurry composition according to [1], wherein the 1,4-butanediol comprises any one of 1,4-butanediol produced by direct fermentation of sugar, 1,4-butanediol produced by hydrogen reduction of succinic acid or a succinic acid derivative produced using a biomass resource, 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 includes 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 cm as measured by the krypton adsorption method. 2 / g or more, and the average particle size D is measured by the sieve method in accordance with ASTM D1921-06 and calculated in accordance with ISO 9276-2:2014. 50 A method for producing a slurry composition, characterized in that the slurry composition is in the form of particles of 40 μm or more and 200 μm or less.

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

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

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

[0022] [8] A method for producing polybutylene terephthalate, which uses a slurry composition produced by the method for producing a slurry composition according to any one of [4] to [6]. [Effects of the Invention]

[0023] The slurry composition of the present invention has excellent resistance to sedimentation of terephthalic acid in the slurry composition. Therefore, even in the event of an incident in which the stirring or fluidizing state of the slurry composition cannot be maintained due to equipment failure or the like, the slurry composition can be prevented from sedimenting, thereby enabling stable production with excellent handleability in the production of polybutylene terephthalate by a direct polymerization method. Furthermore, since the uniform dispersion state of terephthalic acid and 1,4-butanediol in the slurry composition can be stably maintained, when this slurry composition is used as a raw material for polybutylene terephthalate, the esterification reaction rate is high and the esterification reaction proceeds in a shorter time. In other words, polybutylene terephthalate can be produced more stably and in a shorter time, and its industrial value is extremely high. DETAILED DESCRIPTION OF THE INVENTION

[0024] The present invention will be described in detail below, but the explanation of the constituent elements described below is a representative example of an embodiment of the present invention, and the present invention is not limited to these contents. In the present invention, the "main component" of the dicarboxylic acid component refers to a component that accounts for 50 mol % or more of the dicarboxylic acid component. The same applies to the "main component" of the diol component. Also, "ppm" refers to "ppm by mass."

[0025] [Slurry Composition] The slurry composition of the present invention contains terephthalic acid and 1,4-butanediol, and the terephthalic acid in the slurry composition has a BET specific surface area of ​​1,500 cm as measured by a krypton adsorption method. 2 / g or more, and the average particle size D is measured by the sieve method in accordance with ASTM D1921-06 and calculated in accordance with ISO 9276-2:2014. 50 (Hereinafter, simply referred to as "average particle size D 50 It is sometimes referred to as ".) It is characterized by being in the form of particles of 40 μm or more and 200 μm or less.

[0026] In the present invention, the BET specific surface area and average particle size D 50 is the BET specific surface area and average particle size D of terephthalic acid before it is mixed with 1,4-butanediol to form a slurry composition. 50 However, this BET specific surface area and average particle size D 50 is the BET specific surface area and average particle size D of terephthalic acid in the slurry composition. 50 matches. That is, since terephthalic acid does not exhibit 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 average particle size D of terephthalic acid before being mixed with 1,4-butanediol to form a slurry composition are 50 is the BET specific surface area and average particle size D of terephthalic acid in the slurry composition. 50 matches.

[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 (petrochemical-derived terephthalic acid), 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 plant-derived raw materials such as corn or sugarcane. The terephthalic acid of the present invention may be a mixture of two or more kinds of terephthalic acids having different origins. When two or more kinds of terephthalic acids are mixed, the BET specific surface area and the average particle size D 50 is the measurement of terephthalic acid as a mixture. From the viewpoint 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. From the same viewpoint, 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 measured by krypton gas adsorption method. 2 / g or more. This BET specific surface area is 1500 cm 2 / g or more, preferably 1800 cm 2 / g or more, more preferably 2000 cm 2 / g or more, more preferably 2500 cm 2 / g or more, and 3500 cm 2 On the other hand, the upper limit of the BET specific surface area of ​​the terephthalic acid of the present invention is preferably 5000 cm 2 / g or less, more preferably 4900 cm 2 / g or less, more preferably 4800 cm 2 / g or less. If the BET specific surface area of ​​terephthalic acid is less than the lower limit of the above range, the sedimentation tendency of terephthalic acid in the slurry composition increases and the esterification reaction rate slows down, which is undesirable.If the BET specific surface area of ​​terephthalic acid is equal to or greater than the above lower limit, the area in contact with BDO increases, the resistance to sedimentation increases, and the sedimentation tendency decreases. The larger the BET specific surface area of ​​terephthalic acid, the lower the sedimentation property. However, it is difficult and unrealistic to produce terephthalic acid having a BET specific surface area exceeding the upper limit of the above range. When the BET specific surface area of ​​the terephthalic acid is within the above range, the effects of the present invention are excellent and the practicality is also excellent.

[0029] Terephthalic acid having a BET specific surface area within the above range can be obtained by adjusting the purification conditions in the production process of terephthalic acid. Furthermore, the BET specific surface area can also be adjusted by subjecting the purified terephthalic acid to crystallization. For example, in a purification operation in which terephthalic acid is stirred and mixed with water under heat and pressure, followed by filtration, low temperature conditions and strong stirring conditions can be used to obtain terephthalic acid with a large BET specific surface area. Conversely, high temperature conditions and weak stirring conditions can be used to obtain terephthalic acid with a small BET specific surface area. Furthermore, if the BET specific surface area of ​​the terephthalic acid to be purified is large, terephthalic acid with a large BET specific surface area can be obtained, and conversely, if the BET specific surface area of ​​the terephthalic acid to be purified 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 D 50 The essential requirement is that the average particle size D is 40 μm or more. 50 On the other hand, the average particle diameter D of the terephthalic acid of the present invention is 40 μm or more, preferably 45 μm or more, more preferably 50 μm or more, even more preferably 60 μm or more, and most preferably 70 μm or more, and 80 μm or more. 50 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 diameter D of the terephthalic acid is less than the lower limit of the above range, the handling property becomes poor when the terephthalic acid is treated as a powder, which is not preferable. 50 When the average particle diameter D is equal to or greater than the above lower limit, dust of terephthalic acid is less likely to fly around during handling in producing the slurry, and handling is excellent. 50 When PBT is produced using terephthalic acid having a t-value of at least the above lower limit, the esterification reaction rate is high, which is preferable. On the other hand, the average particle size of terephthalic acid D 50 If the average particle diameter D exceeds the upper limit of the above range, the terephthalic acid in the slurry composition tends to settle easily. 50 is preferably small.

[0031] Average particle size D 50 Terephthalic acid having an average particle size D in the above range can be obtained by adjusting the purification conditions in the production process of terephthalic acid. Furthermore, the average particle size D can also be obtained by subjecting purified terephthalic acid to crystallization. 50 can be adjusted. For example, in the purification process of mixing terephthalic acid with water under heat and pressure, followed by filtration, by adopting low temperature conditions and strong stirring conditions, the average particle size D 50 On the other hand, by adopting high temperature conditions and weak stirring conditions, it is possible to obtain terephthalic acid with a small average particle size D 50 Therefore, terephthalic acid having a high molecular weight can be obtained. In addition, if the particle size of the terephthalic acid to be purified is large, the average particle size D 50 On the other hand, if the particle size of the terephthalic acid to be purified is small, the average particle size D 50 Therefore, terephthalic acid having a low molecular weight can be obtained.

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

[0033] From the perspective of aiming for a sustainable society for the global environment and future generations, the BDO used in the present invention is preferably biomass-derived BDO or chemically recycled BDO.

[0034] Biomass-derived 1,4-butanediol may be produced by direct fermentation of sugars, or by producing succinic acid or a succinic acid derivative from a biomass resource and then reducing it with hydrogen. Examples of succinic acid derivatives include succinic anhydride and succinic acid esters such as dialkyl succinates (more specifically, dialkyl succinates having an alkyl group with 1 to 4 carbon atoms, preferably 1 to 3, more preferably 1 to 2, and most preferably a methyl group with 1 carbon atom). In any of the BDO production methods, it is preferable to carry out distillation purification or hydrogenation purification in each step as necessary.

[0035] Furthermore, examples of chemically recycled 1,4-butanediol include chemically recycled 1,4-butanediol obtained by depolymerizing polybutylene terephthalate, as disclosed in Patent Document 5.

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

[0037] When biomass-derived 1,4-butanediol is used as the raw material for producing polybutylene terephthalate, the 1,4-butanediol in the composition of the present invention is preferably biomass-derived 1,4-butanediol. Furthermore, when chemically recycled 1,4-butanediol is used as the 1,4-butanediol used as a raw material for producing polybutylene terephthalate, the 1,4-butanediol in the composition of the present invention is preferably chemically recycled 1,4-butanediol.

[0038] <Content ratio of terephthalic acid and BDO> The ratio of terephthalic acid to BDO in the slurry composition of the present invention varies depending on the content of other copolymerization components in the slurry composition. However, from the viewpoint of using the composition as a raw material for producing polybutylene terephthalate, the BOD is preferably contained in the slurry composition of the present invention so that the BOD is 1.6 mol or more per mol of terephthalic acid, more preferably 1.7 mol or more, and even more preferably 1.8 mol or more. A ratio of less than 1.6 mol is undesirable because the viscosity of the slurry composition increases and the flowability of the slurry composition decreases. 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. Therefore, a ratio of 2.2 mol or less, particularly 2.0 mol or less, and especially 1.9 mol or less is preferred. 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, which is preferable.

[0039] The slurry composition of the present invention may be composed only of terephthalic acid and 1,4-butanediol, or may contain dicarboxylic acid components other than terephthalic acid, diol components other than BDO, copolymerization components other than these dicarboxylic acid components and diol components, and a polycondensation catalyst, which are used in the production of PBT described below. However, in view of the effect of terephthalic acid on the sedimentation resistance and the effect of improving esterification reactivity 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 to 100% by mass. In particular, the sedimentation resistance of terephthalic acid is preferably evaluated for a slurry composition composed of terephthalic acid and BDO.

[0040] <Method for producing slurry composition> The slurry composition of the present invention has the above-mentioned BET specific surface area and average particle size D 50 The terephthalic acid of the present invention and BDO that satisfy the above condition can be mixed and stirred until the mixture is 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 more, particularly preferably 15° C. or more. The temperature of the slurry composition is preferably the same as the temperature at which the slurry is prepared.

[0041] [Manufacturing method of polybutylene terephthalate] The method for producing polybutylene terephthalate of the present invention using the slurry composition of the present invention will be described below. Hereinafter, 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, with 50 mol % or more of the dicarboxylic acid component being terephthalic acid and 50 mol % or more of the diol component being BDO. The proportion of terephthalic acid in all dicarboxylic acid components is preferably 70 mol % or more, more preferably 80 mol % or more, and particularly preferably 95 mol % or more, and the proportion of BDO in all diol components is preferably 70 mol % or more, more preferably 80 mol % or more, and even more preferably 95 mol % or more. If the proportion of terephthalic acid or BDO is less than 50 mol %, the crystallization rate of PBT decreases, resulting in poor moldability. In the method for producing polybutylene terephthalate of the present invention, the slurry composition of the present invention is used as at least a part 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. Dicarboxylic acids other than terephthalic acid that can be used as raw materials for producing PBT are not particularly limited, and 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'-diphenylsulfonedicarboxylic 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. Dicarboxylic acid derivatives include esters of these dicarboxylic acids and ester-forming derivatives such as dicarboxylic acid halides. These dicarboxylic acid components other than terephthalic acid may be used alone or in combination of two or more. Dicarboxylic acid components such as succinic acid may be derived from chemical recycling or biomass.

[0044] In the present invention, the diol component other than BDO is not particularly limited, and examples thereof 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 alone or in combination of two or more. Diol components other than BDO may also be derived from biomass or chemical recycling.

[0045] In the present invention, further, hydroxycarboxylic acids such as lactic acid, glycolic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, 6-hydroxy-2-naphthalenecarboxylic 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. can be used as one or more copolymer 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 the water and excess diol component 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 to form an ester) 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 the melt polycondensation step is a method in which a single melt polycondensation tank or a multistage reaction apparatus in which a plurality of melt polycondensation tanks are connected in series, and the multistage reaction apparatus comprises, for example, a first-stage complete mixing reactor equipped with stirring blades and second-stage and third-stage horizontal plug-flow reactors equipped with stirring blades, is used, and the diol produced is distilled out of the system while heating under reduced pressure in the presence of a catalyst.

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

[0050] The reaction vessel may be a single vessel or multiple vessels, but in order to prevent coloration and deterioration and to suppress an increase in terminal groups such as vinyl groups, it is advisable to carry out the reaction in at least one vessel under a high vacuum of usually 1.3 kPa or less, preferably 0.3 kPa or less. The reaction rate can be increased by, for example, increasing the degree of vacuum, accelerating the rate of temperature rise, or increasing the rate of renewal of the reaction liquid surface.

[0051] The PBT obtained by the polycondensation reaction is usually withdrawn in the form of a strand or sheet from a withdrawal port provided at the bottom of the polycondensation reaction tank, and then cut with a cutter while being cooled with water or after being cooled with water to form granular bodies such as pellets or chips (for example, lengths of about 3 to 10 mm).

[0052] <Polycondensation catalyst> When the oligomer obtained by the esterification reaction of the diol component and the dicarboxylic acid component is polycondensed, a titanium compound and preferably a compound of a metal of Group 2A of the Periodic Table are usually used as catalysts. These catalyst components may be used in the esterification reaction and then directly subjected 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 catalyst amount ultimately used may be used in the esterification reaction, and then appropriately added as the polycondensation reaction proceeds. In any case, in the present invention, titanium and preferably a metal from Group 2A of the Periodic Table are inevitably contained in the PBT finally obtained, and the amounts thereof will be described later.

[0053] Specific examples of titanium compounds include inorganic titanium compounds such as titanium oxide and titanium tetrachloride, titanium alcoholates such as tetramethyl titanate, tetraisopropyl titanate and tetrabutyl titanate, titanium phenolates such as tetraphenyl titanate, etc. These may be used alone or in combination of two or more. Of these, tetraalkyl titanates are preferred, and among these, tetrabutyl titanate is preferred.

[0054] The content of the titanium catalyst in the PBT of the present invention is preferably 5 to 100 ppm by mass of titanium atoms relative to the PBT. This amount is more preferably 10 ppm or more, even more preferably 20 ppm or more, and most preferably 25 ppm or more. This amount is 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 tone, hydrolysis resistance, and solution haze will deteriorate, and the number of fish eyes will increase in the resulting molded product, while if the titanium content is too low, the polymerization property will deteriorate.

[0055] Specific examples of the compound of a metal of Group 2A of the Periodic Table in the present invention include various compounds of beryllium, magnesium, calcium, strontium, and barium. From the viewpoints of ease of handling and availability, and catalytic effect, magnesium compounds and / or calcium compounds are preferred, and magnesium compounds, which have excellent catalytic effect, are particularly preferred. Specific examples of magnesium compounds include magnesium acetate, magnesium hydroxide, magnesium carbonate, magnesium oxide, magnesium alkoxide, magnesium hydrogen phosphate, and the like. 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 is preferably 3 to 150 ppm in terms of the mass ratio of the Group 2A metal atom to PBT. 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 a method such as wet ashing.

[0059] In the production of the PBT of the present invention, separately 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 for compounding or 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 tends to be insufficient, while if it exceeds 1.3 dL / g, the melt viscosity tends to be high, which deteriorates the flowability and moldability. 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 such as film, sheet, or filament, the intrinsic viscosity of the PBT is usually 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, extrusion moldability deteriorates, leading to drawdown of the resin and molding defects, resulting in insufficient mechanical strength of extrusion-molded products such as films, or the melt viscosity decreases, resulting in excessively high fluidity and thus poor extrusion moldability. On the other hand, if the intrinsic viscosity exceeds 1.60 dL / g, the melt viscosity increases, resulting in poor fluidity and thus poor extrusion moldability.

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

[0063] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples in any way as long as the gist of the invention is not exceeded. The methods for measuring 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 were subjected to reduced pressure heating treatment at 150°C under vacuum for 2 hours, and the adsorption isotherm (adsorbed gas: krypton) was measured at liquid nitrogen temperature. The obtained adsorption isotherm was used to perform BET multipoint analysis and calculate the specific surface area. The adsorption cross section of krypton was 0.205 nm 2 was analyzed as.

[0065] (2) Average particle size D of terephthalic acid 50 It was measured by the sieve 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 1.80 mol of BDO with 1.00 mol of terephthalic acid, and the mixture was stirred until it became sufficiently uniform. This slurry was placed in a 1000 mL measuring cylinder and allowed to stand at 60°C for 1 hour. After standing for 1 hour, the supernatant ratio (the ratio of the scale of the supernatant to the total volume) was measured. The smaller this ratio, the better the resistance to sedimentation of terephthalic acid. In other words, the easier it is to handle the slurry. This value is preferably 10% or less.

[0067] (4) Intrinsic viscosity (IV) of PBT The viscosity was measured using an Ubbelohde viscometer according to the following procedure. Using a mixed solvent of phenol / tetrachloroethane (1 / 1 mass ratio), the number of seconds it took for a polymer solution with a concentration of 1.0 g / dL and the solvent alone to fall at 30° C. was measured 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 is Huggins' constant, which we used as 0.33.)

[0068] (5) Titanium and Group 2A metal concentrations in PBT PBT was wet decomposed with high-purity sulfuric acid and nitric acid for the electronics industry, and the content of PBT was measured using a high-resolution ICP (Inductively Coupled Plasma)-MS (Mass Spectrometer) (manufactured by ThermoQuest).

[0069] [BET specific surface area and average particle size D of petrochemically derived terephthalic acid 50 Adjustment In the following examples and comparative examples, commercially available high-purity terephthalic acid (PTA) (high-purity terephthalic acid manufactured by PT Mitsubishi Chemical Indonesia) produced by oxidizing petrochemical-derived p-xylene 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 reaction, was used as terephthalic acid. By carrying out the following treatment, the BET specific surface area and average particle size D 50 The adjusted value 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. 3 The stirring was carried out under stirring conditions of about 0.5 to 5 horsepower per minute and a linear velocity of the stirring blade of about 0.5 to 5 m / s, and the mixture was treated at a temperature of 150 to 250°C for several hours. After filtering at the treatment temperature, the mixture was cooled to room temperature to extract terephthalic acid. By changing the temperature, time, and stirring conditions of this operation, various BET specific surface areas and average particle diameters D 50 of terephthalic acid was obtained. In this purification treatment, the BET specific surface area tends to increase as the treatment temperature decreases, and tends to decrease as the treatment temperature increases. Regarding the stirring conditions, the BET specific surface area tends to increase as the stirring horsepower and stirring linear velocity increase. Furthermore, even when treated under the same conditions, if the surface area of ​​the treated terephthalic acid is large, the resulting terephthalic acid will have a large BET specific surface area, and if the surface area of ​​the treated terephthalic acid is small, the resulting terephthalic acid will have a small BET specific surface area. Average particle size D 50Regarding the mixing conditions, the higher the mixing horsepower and the mixing linear velocity, the larger the average particle size D 50 Even when treated under the same conditions, if the particle size of the treated terephthalic acid is large, the average particle size D 50 When the particle size of the treated terephthalic acid is small, the average particle size D 50 The resulting product is terephthalic acid, which has a small molecular weight.

[0070] In this way, various BET specific surface areas and average particle diameters D 50 We obtained petrochemically derived terephthalic acid. The BET specific surface area and average particle size D obtained by the above treatment 50 The BET specific surface area and average particle size D shown in Tables 1 to 3 for each Example and Comparative Example were measured by using petroleum-derived terephthalic acid having different properties, either alone or by appropriately blending treated terephthalic acid and untreated terephthalic acid. 50 Petrochemically derived terephthalic acid was prepared and used.

[0071] [Production of biomass-derived 1,4-butanediol] <Production Example 1: 1,4-Butanediol by Hydrogenation of Biomass-Derived Succinic Acid Ester> A mixture was obtained by mixing BDO manufactured by Yuanli Chemical Group and BDO manufactured by Zhejiang Boju New Materials Co., Ltd. The mixture was distilled under reduced pressure to obtain a first fraction, a main fraction, and a second fraction in the order of distillation. A portion of the main fraction was extracted and analyzed by gas chromatography, which revealed that the 1,4-butanediol content was 99% by mass or more.

[0072] [Production of chemically recycled 1,4-butanediol] <Production Example 2: 1,4-Butanediol by Depolymerization of PBT> Chemically recycled BDO was produced in accordance with Example 3 of JP-A-2004-323378. An autoclave equipped with a stirring blade was charged with 1,030 parts by mass of polybutylene terephthalate, 3,200 parts by mass of methanol, and 13 parts by mass of sodium carbonate. The autoclave was immersed in an oil bath at 200°C, and the mixture was reacted for 8 hours with stirring at a pressure of 1.3 MPa. The autoclave was removed from the oil bath and cooled to below 10°C with ice water to obtain a slurry. The resulting slurry was separated into solid and liquid using filter paper to obtain a filtrate. The filtrate was placed in a distillation apparatus equipped with a thermometer, a pressure reduction controller, a stirring blade, a condenser, and a distillate receiver. After recovering methanol and tetrahydrofuran as the initial fraction, the mixture was distilled under reduced pressure to obtain the initial fraction, main fraction, and subsequent fraction in the order of distillation. A portion of the obtained main fraction was extracted and analyzed by gas chromatography, which revealed that the 1,4-butanediol content was 99% by mass or more.

[0073] [Production of Chemically Recycled Terephthalic Acid and Its BET Specific Surface Area and Average Particle Size D 50 Adjustment <Production Example 3: Production of Chemically Recycled Terephthalic Acid 1 and Its BET Specific Surface Area and Average Particle Size D 50 Adjustment > Chemically recycled dimethyl terephthalate 1 was obtained as follows, with reference to the method described in JP-A-2001-151934. A flask equipped with a fraction recovery receiver, a stirrer, and a thermometer was charged with 100 parts by mass of polyethylene terephthalate waste fiber, 100 parts by mass of ethylene glycol, and 1.5 parts by mass of sodium carbonate. The flask was immersed in an oil bath at 210°C, and the mixture was reacted for 10 hours while removing low-boiling components, yielding depolymerization reaction solution 1. The obtained depolymerization reaction solution 1 was filtered while hot using a glass filter, yielding 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 the mixture was reacted at 65° C. for 1 hour to obtain reaction liquid 2. The resulting reaction liquid 2 was placed in a vacuum distillation apparatus equipped with a fraction collection receiver, a Liebig condenser, a stirrer, a thermometer, and a pressure controller. The distillation apparatus was immersed in an oil bath, and the temperature and pressure of the oil bath were controlled while monitoring the distillate. The initial fraction, main fraction, and bottoms were obtained in the order of distillation. The resulting main fraction and xylene were placed in an eggplant flask and heated to form a homogeneous solution. The solution was then cooled to room temperature for crystallization to obtain a slurry. The resulting slurry was filtered through a glass filter to obtain a cake. The resulting cake was placed in an eggplant flask and attached to an evaporator equipped with an oil bath. The xylene was distilled off from the cake under reduced pressure to obtain a white solid (chemically recycled dimethyl terephthalate 1). A portion of the resulting white solid was extracted and analyzed by gas chromatography. The dimethyl terephthalate content was found to be 99% by mass or more.

[0074] The resulting white solid dimethyl terephthalate 1 was dissolved in methylene chloride, and a methanol solution of potassium hydroxide was added thereto for hydrolysis, yielding reaction liquid 1. The resulting reaction liquid 1 was neutralized with 60% by mass of sulfuric acid to yield slurry 2. The resulting slurry 2 was filtered using a centrifuge to yield cake 2. The resulting cake 2 was added to pure water and mixed to yield slurry 3. The resulting slurry 3 was filtered using a centrifuge to yield cake 3. The resulting cake 3 was again added to pure water and mixed to yield slurry 4. The resulting slurry 4 was filtered using a centrifuge to yield cake 4. The resulting cake 4 was placed in an eggplant flask and attached to an evaporator equipped with an oil bath. Low-boiling components were distilled off from cake 4 under reduced pressure, yielding chemically recycled terephthalic acid 1 as a white solid. A portion of the resulting white solid was analyzed by liquid chromatography, and the terephthalic acid content was found to be 99% by mass or more. The resulting white solid of chemically recycled terephthalic acid 1 was crystallized to obtain a BET specific surface area of ​​2050 cm 2 / g, average particle size D 50 Chemically recycled terephthalic acid 1 with a particle size of 132 μm was obtained.

[0075] <Production Example 4: Production of Chemically Recycled Terephthalic Acid 2 and Its BET Specific Surface Area and Average Particle Size D 50 Adjustment > Chemically recycled dimethyl terephthalate 2 was obtained as follows, with reference to the method described in JP-A-2004-323378. An autoclave equipped with a stirrer and a thermometer was charged with 100 parts by mass of polyethylene terephthalate waste fiber, 300 parts by mass of methanol, and 1.5 parts by mass of sodium carbonate. The autoclave was immersed in an oil bath at 150°C, and the reaction was carried out at 1.3 MPa for 10 hours. Thereafter, a distillation tube was attached to the autoclave, and the pressure was slowly reduced to normal pressure to distill off low-boiling components, thereby obtaining depolymerization reaction solution 1. The temperature of the obtained depolymerization reaction liquid 1 was then lowered to room temperature, followed by the addition of xylene, 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 subjected to solid-liquid separation using a centrifuge to obtain cake 2. The obtained cake 2 was placed in a flask equipped with a fraction collection receiver, a stirrer, and a thermometer, and then immersed in an oil bath. The temperature and pressure of the oil bath were controlled while monitoring the distillate, and the initial fraction, main fraction, and bottoms were obtained in the order of distillation. A portion of the obtained main fraction was extracted and analyzed by gas chromatography, revealing that the dimethyl terephthalate content was 99% by mass or more. Instead of dimethyl terephthalate 1, the main fraction of this dimethyl terephthalate (chemically recycled dimethyl terephthalate 2) was used, and hydrolysis and purification were carried out in the same manner as in Production Example 3 to obtain chemically recycled terephthalic acid 2 as a white solid having a terephthalic acid content of 99% by mass or more. The resulting white solid of chemically recycled terephthalic acid 2 was crystallized to obtain a BET specific surface area of ​​2080 cm 2 / g, average particle size D 50 Chemically recycled terephthalic acid 2 with a particle size of 131 μm was obtained.

[0076] <Production Example 5: Production of Chemically Recycled Terephthalic Acid 3 and Its BET Specific Surface Area and Average Particle Size D 50 Adjustment > Chemically recycled dimethyl terephthalate 3 was obtained as follows, with reference to the method described in JP-A-2001-151934. An autoclave equipped with a stirrer and thermometer was charged with 100 parts by mass of glass filler-containing polybutylene terephthalate and 200 parts by mass of methanol. The autoclave was immersed in an oil bath at 170°C and reacted at 5.5 MPa for 5 hours. The autoclave was then removed from the oil bath and cooled to room temperature to obtain depolymerization reaction solution 1. The resulting depolymerization reaction solution 1 was filtered through a glass filter to obtain a solid fraction. Tetrahydrofuran was added to the resulting solid fraction to dissolve the white solid contained in the solid fraction. The glass filler was removed as a filtrate by filtration to obtain solution 1. The resulting solution 1 was placed in a flask equipped with a fraction collection receiver, a stirrer, and a thermometer and then immersed in an oil bath. The temperature and pressure of the oil bath were controlled while monitoring the distillate, and low-boiling components containing tetrahydrofuran, the initial fraction, the main fraction, and the bottoms were collected in the order of distillation. A portion of the resulting main fraction was extracted and analyzed by gas chromatography. The dimethyl terephthalate content was found to be 99% by mass or more. Instead of dimethyl terephthalate 1, the main fraction of this dimethyl terephthalate (chemically recycled dimethyl terephthalate 3) was used, and hydrolysis and purification were carried out in the same manner as in Production Example 3 to obtain chemically recycled terephthalic acid 3 as a white solid having a terephthalic acid content of 99% by mass or more. The resulting white solid of chemically recycled terephthalic acid 3 was crystallized to give a BET specific surface area of ​​2060 cm 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 the terephthalic acid of different origins used in each of the Examples and Comparative Examples shown in Tables 1 to 3 below are 50 From the values ​​of BET specific surface area and average particle size D 50 There is no correlation between the average particle size D 50 In addition, a small BET specific surface area does not necessarily mean that the average particle size D50 The BET specific surface area and average particle size D 50 It can be seen that this is a physical property independent of the

[0078] [Example 1] PBT was produced as follows:

[0079] The BET specific surface area and average particle size D shown in Table 1 50 1.00 mol of petroleum-derived terephthalic acid was mixed with 1.80 mol of petroleum-derived BDO (manufactured by Mitsubishi Chemical Corporation) and thoroughly stirred at 60°C until homogeneous. When the sedimentation of terephthalic acid in this slurry was evaluated, the ratio of the supernatant liquid portion after standing at 60°C for 1 hour was 5%. This slurry was continuously fed to an esterification reactor equipped with a screw agitator and filled with PBT oligomer with an esterification rate of 99%, where the esterification reaction was carried out. A BDO solution containing a tetrabutyl titanate catalyst in an amount to give a titanium content of 40 ppm relative to the PBT was fed to the esterification reactor. Additional BDO was fed to the esterification reactor so that the molar ratio of BDO to terephthalic acid was 3.2. The reactor temperature 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] The PBT oligomer with an esterification rate of 96.5% was then continuously transferred to a first polycondensation reaction tank. In the first polycondensation reaction tank, a continuous polycondensation reaction was carried out in the presence of magnesium acetate tetrahydrate catalyst in an amount such that the magnesium content relative to the PBT was 10 ppm. The reaction temperature was 230°C, the pressure was 3.9 kPa, and the average residence time was 120 minutes. This product was then transferred to a second polycondensation reaction tank, where a continuous polycondensation reaction was carried out. The reaction temperature was 240°C, the pressure was 130 Pa, and the average residence time was 80 minutes.

[0081] The obtained polymer was passed through a discharge line by a discharge gear pump, passed through a filter, and continuously discharged in the form of strands from a die head. The strands were then cut with a rotary cutter to obtain PBT pellets (major axis approximately 3 mm, minor axis approximately 2 mm, length approximately 4 mm). The intrinsic viscosity (IV) of the resulting PBT was 0.85 dL / g. The results are summarized in Table 1.

[0082] [Examples 2 to 15, Comparative Examples 1 to 5] In Example 1, the raw material terephthalic acid was selected from the group consisting of terephthalic acid having a BET specific surface area and an average particle size D 50 PBT was obtained in the same manner as in Example 1 except that terephthalic acid derived from each of the descriptions in Tables 1 to 3 was used, and BDO derived from each of the descriptions in Tables 1 to 3 was used, and evaluation was performed in the same manner. The results are shown in Tables 1 to 3. In Tables 1 to 3, "chemically recycled" is abbreviated as "CR," "petrochemically derived" is abbreviated as "petrochemical," and "biomass-derived" is abbreviated as "bio." Therefore, "chemically recycled terephthalic acid 1" obtained in Production Example 3 is abbreviated as "CRTPA1," "chemically recycled terephthalic acid 1" obtained in Production Example 4 is abbreviated as "CRTPA2," and "chemically recycled terephthalic acid" obtained in Production Example 5 is abbreviated 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 are excellent in resistance to settling of terephthalic acid and also in esterification reactivity (short average residence time in the esterification tank). Furthermore, this effect can be obtained not only when petroleum-derived terephthalic acid is used as the terephthalic acid, but also when chemically recycled terephthalic acid is used. It can also be obtained when biomass-derived BDO or chemically recycled BDO is used, not only when petroleum-derived BDO is used. In contrast, the slurry compositions of Comparative Examples 1 to 5 in Table 3, which do not satisfy the requirements of the present invention, were inferior in both sedimentation resistance and esterification reactivity of terephthalic acid.

Claims

1. A slurry composition comprising terephthalic acid and 1,4-butanediol, The terephthalic acid has a BET specific surface area of ​​1,500 cm as measured by the krypton adsorption method. ２ / g or more, and the average particle size D is measured by the sieve method in accordance with ASTM D1921-06 and calculated in accordance with ISO 9276-2:2014. ５０ A slurry composition characterized in that the particles are in the form of particles of 40 μm or more and 200 μm or less.

2. 2. The slurry composition according to claim 1, wherein the 1,4-butanediol comprises any one of 1,4-butanediol produced by direct fermentation of sugar, 1,4-butanediol produced by hydrogen reduction of succinic acid or a succinic acid derivative produced using a biomass resource, 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, comprising: The terephthalic acid has a BET specific surface area of ​​1,500 cm as measured by the krypton adsorption method. ２ / g or more, and the average particle size D is measured by the sieve method in accordance with ASTM D1921-06 and calculated in accordance with ISO 9276-2:2014. ５０ A method for producing a slurry composition, characterized in that the slurry composition is in the form of particles having a size of 40 μm or more and 200 μm or less.

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

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

7. A method for producing polybutylene terephthalate, which uses the slurry composition according to any one of claims 1 to 3.

8. A method for producing polybutylene terephthalate, which uses a slurry composition produced by the method for producing a slurry composition according to any one of claims 4 to 6.

Images