Isophthalic acid-copolymerized polybutylene terephthalate composition and process for producing the same

Abstract

To provide an isophthalic acid-copolymerized polybutylene terephthalate composition having excellent molding cycle characteristics and giving a molded article having excellent fitting properties and hinge characteristics.SOLUTION: An isophthalic acid-copolymerized polybutylene terephthalate composition having an isophthalic acid copolymerization amount of 0.1 to 2.0 mol%, obtained by reacting isophthalic acid-copolymerized polybutylene terephthalate obtained by copolymerizing isophthalic acid with a reaction product of dimethyl terephthalate or terephthalic acid and 1, 4-butanediol.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an isophthalic acid-copolymerized polybutylene terephthalate (hereinafter sometimes abbreviated as "PBT") composition, which is polybutylene terephthalate copolymerized with isophthalic acid (hereinafter sometimes abbreviated as "IPA"). The present invention also relates to a method for producing an isophthalic acid-copolymerized polybutylene terephthalate (hereinafter sometimes abbreviated as "IPA-copolymerized PBT") composition, which can improve the accuracy of the copolymerization amount of the isophthalic acid-copolymerized polybutylene terephthalate (hereinafter sometimes abbreviated as "IPA-copolymerized PBT") composition. [Background technology]

[0002] Polybutylene terephthalate (PBT) has excellent mechanical properties, heat resistance, moldability, and recyclability, as well as high mechanical strength and excellent chemical resistance, and is therefore 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, which has led to a demand for high-quality PBT with excellent productivity.

[0003] In recent years, in the automotive field, with the advancement of electronics and the addition of functions to improve safety, comfort, and driving performance, the number of electrical components installed in each vehicle, particularly connectors such as wire harnesses, has increased, and the number of PBT parts used in these has also increased.In addition, new needs have arisen, such as thinner connectors to accommodate the increasing number of circuits, and multi-circuit connectors to curb the increase in the number of circuits installed, and as a result, PBT is being required to have more advanced material properties such as dimensional stability, toughness, and fluidity.

[0004] Wire harness connectors are connecting components at both ends of a wire harness, which groups together the electric wires in an automobile at required locations, and they transmit electricity to the appropriate circuits while also fixing the wire harness in place. For this reason, wire harness connectors are required to have the same appropriate electrical characteristics and safety as electric wires. Furthermore, in recent years, in order to achieve further improvements in quality and productivity in the molding of wire harness connectors, there is a demand for materials that combine stable moldability and a short molding cycle in addition to the above material properties, and development is being considered for PBT, which has the advantage of being one of the fastest cooling and solidifying crystalline resins.

[0005] PBT is a crystalline resin, and molded PBT products crystallize. If crystallization is slow during injection molding, the molded product takes a long time to solidify, necessitating a longer cooling time after injection molding, which can lengthen the molding cycle and reduce productivity. This molding cycle can be evaluated by the ease of release of the resulting molded product and the presence or absence of ejector pin marks when injection molding is performed under certain molding conditions. As the crystallization rate slows, ejector pin marks appear, and if the crystallization rate slows further, release becomes impossible. Furthermore, even for connectors of the same shape, differences in crystallization during solidification can occur depending on the molding machine model, molding time, and position within the multi-cavity mold. These differences in crystallization can result in differences in the cooling and solidification speed and crystallization temperature for each molded product. If crystallization does not progress sufficiently during molding, but progresses after molding, dimensional changes due to post-shrinkage become significant, resulting in poor fit when used as a connector. Furthermore, reduced toughness can lead to breakage and cracking. On the other hand, the recent trend towards lighter, thinner, shorter and smaller molded products has necessitated further improvements in the precision required when mating connectors.

[0006] In the conventional material requirements for connector applications, changes in material properties and moldability due to differences in cooling solidification speed and crystallization temperature were not a major problem. However, new needs for thinner walls and more circuits in wire harness connector applications have created demands for more stable material properties such as dimensional accuracy and toughness. This has created a need to solve the problem of wire harness connectors using PBT, where material properties change due to variations in moldability, making it impossible to obtain molded products that meet these needs.

[0007] Patent Document 1 describes a PBT composition made by compounding IPA copolymer PBT and homo PBT as a PBT composition applicable to connector applications used in automotive components and electrical and electronic components. However, in PBT compositions produced by simply compounding and mixing IPA copolymer PBT and homo PBT, depending on the compounding conditions, the resin mixing is inferior to that of copolymer resins, resulting in variations in the properties of the resulting PBT composition. If this mixing is poor, the desired properties may not be obtained, and improvements are desired. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-189787 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention aims to solve the above-mentioned problems of the conventional art and to provide an IPA copolymer PBT composition that is excellent in molding cycle characteristics and that produces molded articles with excellent fit-fitting properties and hinge characteristics, and a method for producing the IPA copolymer PBT composition that can produce the IPA copolymer PBT composition with high precision in the amount of IPA copolymerized. [Means for solving the problem]

[0010] As a result of extensive research into solving the above-mentioned problems, the present inventors have found that this problem can be solved by further polymerizing a PBT oligomer composed of dimethyl terephthalate or terephthalic acid and 1,4-butanediol, which are PBT raw materials, with IPA-copolymerized PBT to reduce the amount of IPA copolymerized. The present invention was completed based on these findings, and the gist of the present invention is as follows.

[0011] [1] Isophthalic acid copolymerized polybutylene terephthalate obtained by copolymerizing isophthalic acid, a reaction product of dimethyl terephthalate or terephthalic acid with 1,4-butanediol; is reacted with An isophthalic acid copolymerized polybutylene terephthalate composition having an isophthalic acid copolymerization amount of 0.1 to 2.0 mol %.

[0012] [2] The isophthalic acid-copolymerized polybutylene terephthalate composition according to [1], wherein the amount of the isophthalic acid-copolymerized polybutylene terephthalate used is 1 to 20 mass% based on the total amount of the isophthalic acid-copolymerized polybutylene terephthalate and the reaction product of dimethyl terephthalate or terephthalic acid and 1,4-butanediol.

[0013] [3] The isophthalic acid copolymerized polybutylene terephthalate composition according to [1] or [2], wherein the dimethyl terephthalate is derived from petroleum, chemical recycling, or biomass.

[0014] [4] The isophthalic acid copolymerized polybutylene terephthalate composition according to any one of [1] to [3], wherein the terephthalic acid is derived from petroleum, chemical recycling, or biomass.

[0015] [5] The isophthalic acid copolymerized polybutylene terephthalate composition according to any one of [1] to [4], wherein the 1,4-butanediol is derived from petroleum, chemical recycling, or biomass.

[0016] [6] The isophthalic acid copolymerized polybutylene terephthalate composition according to any one of [1] to [5], wherein the isophthalic acid is derived from petroleum, chemical recycling, or biomass.

[0017] [7] A method for producing an isophthalic acid-copolymerized polybutylene terephthalate composition, comprising producing isophthalic acid-copolymerized polybutylene terephthalate in a polycondensation reaction tank, extracting a portion of the isophthalic acid-copolymerized polybutylene terephthalate produced from the polycondensation reaction tank, and using the polycondensation reaction tank in which the remainder of the isophthalic acid-copolymerized polybutylene terephthalate remains to produce the isophthalic acid-copolymerized polybutylene terephthalate composition. [Effects of the Invention]

[0018] The IPA copolymerized PBT composition of the present invention, in which the IPA copolymerization amount is 0.1 to 2.0 mol %, is excellent in molding cycle characteristics, and the molded article obtained is also excellent in fitability and hinge characteristics. Furthermore, according to the method for producing an IPA-copolymerized PBT composition of the present invention, the amount of IPA copolymerized can be controlled with high precision when producing an IPA-copolymerized PBT with such a small amount of IPA copolymerized, and therefore, these methods are of great industrial value. The IPA copolymerized PBT composition of the present invention can be used in a wide range of applications, including industrial molded products such as connectors, relays, and switches for automobiles and electrical and electronic devices, as well as films, sheets, and fibers (filaments). In particular, due to its excellent fit-fitting properties and hinge properties of molded products, it is industrially useful as a molding material for thin-walled parts and hinge structure parts of electrical parts and connectors. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a schematic diagram showing the cavity numbers of an eight-cavity mold used to evaluate fitability. [Figure 2] Figure 2(a) is a plan view of a hinged specimen for hinge property testing, Figure 2(b) is a side view of the same, Figure 2(c) is an enlarged side view of the hinge part, and Figure 2(d) is a conceptual diagram showing the state of the hinge property test. DETAILED DESCRIPTION OF THE INVENTION

[0020] The following describes in detail an embodiment of the present invention. However, the description of the constituent elements described below is an example of an embodiment of the present invention, and the present invention is not limited to the following description as long as it does not go beyond the gist of the present invention. In this specification, when the expression "to" is used, it is intended to be used as an expression that includes the numerical values ​​or physical property values ​​before and after it. In this specification, "parts by mass" and "parts by weight" have the same meaning, and "% by mass" and "% by weight" have the same meaning. In the present invention, the "main component" of a 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 a diol component. Also, "ppm" indicates "ppm by mass."

[0021] [IPA copolymerized PBT composition] The IPA copolymerized PBT composition of the present invention is an IPA copolymerized PBT composition having an IPA copolymerization amount of 0.1 to 2.0 mol % obtained by reacting an IPA copolymerized PBT obtained by copolymerizing IPA with a reaction product of dimethyl terephthalate (hereinafter sometimes abbreviated as "DMT") or terephthalic acid (hereinafter sometimes abbreviated as "TPA") and 1,4-butanediol (hereinafter sometimes abbreviated as "BDO").

[0022] In the present invention, the "amount of copolymerized IPA" does not necessarily mean only the IPA copolymerized in PBT, but is determined by analyzing the IPA-copolymerized PBT or the IPA-copolymerized PBT composition by the method described in the Examples section below, and may also include some IPA that is not copolymerized in PBT. From this viewpoint, in the present invention, the "IPA copolymerized PBT composition" is referred to as the "IPA copolymerized PBT composition" to distinguish it from the IPA copolymerized PBT used as a raw material for producing one having an IPA copolymerization amount of 0.1 to 2.0 mol %, but it is generally referred to as the "IPA copolymerized PBT". Hereinafter, the IPA copolymer PBT used as a raw material for producing the IPA copolymer PBT composition of the present invention having an IPA copolymerization amount of 0.1 to 2.0 mol % will be referred to as the "raw material IPA copolymer PBT," and the IPA copolymer PBT composition of the present invention obtained from this raw material IPA copolymer PBT will be referred to as the "produced IPA copolymer PBT" or the "IPA copolymer PBT of the present invention."

[0023] [Components of IPA copolymerized PBT] The diol component that makes up the raw material IPA copolymerized PBT and the produced IPA copolymerized PBT is mainly composed of BDO, and the dicarboxylic acid component is mainly composed of dimethyl terephthalate or terephthalic acid, with IPA as the copolymerization component. In other words, in the present invention, IPA-copolymerized PBT refers to a polymer having a structure in which a dicarboxylic acid component containing terephthalic acid or dimethyl terephthalate and IPA is ester-bonded with a diol component containing BDO, in which 50 mol% or more of the dicarboxylic acid component is terephthalic acid or dimethyl terephthalate and 50 mol% or more of the diol component is BDO. If the terephthalic acid or dimethyl terephthalate or BDO is less than 50 mol%, the crystallization rate of the IPA-copolymerized PBT decreases, resulting in poor moldability. The proportion of terephthalic acid or dimethyl terephthalate in all dicarboxylic acid components is preferably 70 mol% or more, more preferably 80 mol% or more, and particularly preferably 90 mol% or more. The combined proportion of terephthalic acid or dimethyl terephthalate and IPA in all dicarboxylic acid components is preferably 70 mol% or more, more preferably 75 mol% or more, particularly preferably 80 mol% or more, and may even be 100 mol%. The proportion of BDO in all diol components is preferably 70 mol % or more, more preferably 80 mol % or more, even more preferably 90 mol % or more, and may be 100 mol %.

[0024] <Terephthalic acid> The terephthalic acid used in the present invention may 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. From the viewpoint of aiming for a sustainable society for the global environment and future generations, the TPA used in the present invention is preferably terephthalic acid derived from chemical recycling. From the same viewpoint, the TPA used in the present invention is preferably a biomass-derived TPA. In the present invention, TPA derived from each of these can be used, and two or more of these may be used in combination.

[0025] <Dimethyl terephthalate> The dimethyl terephthalate used in the present invention can be produced from terephthalic acid synthesized by oxidation of paraxylene, a petrochemical product (petrochemical-derived terephthalic acid), chemically recycled terephthalic acid obtained by recovering and depolymerizing waste 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. From the perspective of aiming for a sustainable society for the global environment and future generations, the terephthalic acid that is the raw material for DMT used in the present invention is preferably terephthalic acid derived from chemical recycling. From the same viewpoint, the terephthalic acid that is the raw material for the DMT of the present invention is preferably biomass-derived terephthalic acid. These terephthalic acids are esterified with methanol under high temperature and pressure conditions, and the esterification reaction mixture is separated and purified to obtain DMT. The DMT may be DMT produced directly by chemical recycling through the depolymerization of polyesters such as polyethylene terephthalate or polybutylene terephthalate, as shown in the Examples section below. In the present invention, DMT derived from each of these can be used, and two or more of these may be used in combination.

[0026] <bdo> There are no particular limitations on the method for producing BDO used in 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). 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.

[0027] Biomass-derived BDO 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).

[0028] Chemically recycled BDO includes chemically recycled BDO obtained by depolymerizing polyesters that use BDO, such as polybutylene terephthalate, as a raw material.

[0029] In any of the methods for producing BDO, it is preferable to carry out distillation purification or hydrogenation purification in each step as necessary.

[0030] The BDO in the present invention may be a mixture of two or more of petroleum-derived BDO, biomass-derived BDO, and chemically recycled BDO.

[0031] <ipa> The isophthalic acid used in the present invention may be isophthalic acid synthesized by oxidation of m-xylene, a petrochemical product (petrochemical-derived isophthalic acid), isophthalic acid derived from chemical recycling obtained by recovering and depolymerizing waste polyester, or isophthalic acid derived from biomass obtained using m-xylene produced from isobutanol or ethanol produced from plant-derived raw materials such as corn or sugarcane. Alternatively, isobutanol can be obtained from a renewable carbon source according to the methods of Examples 1 to 18 of JP-A 2013-506717, and m-xylene can be obtained from the xylene fraction analyzed according to the methods of Examples 13 to 15. The isophthalic acid obtained by oxidizing this m-xylene can also be used. From the perspective of aiming for a sustainable society for the global environment and future generations, the IPA used in the present invention is preferably isophthalic acid derived from chemical recycling. From the same viewpoint, the IPA used in the present invention is preferably biomass-derived IPA.

[0032] In the present invention, IPAs derived from each of these can be used, and two or more of these IPAs may be used in combination.

[0033] <Raw material IPA copolymerized PBT> The amount of IPA copolymerized in the raw material IPA-copolymerized PBT used to produce the IPA-copolymerized PBT of the present invention is not particularly limited, but it is preferably larger than the amount of IPA copolymerized in the produced IPA-copolymerized PBT, and is preferably 4 to 35 mol %. If the IPA copolymerization amount of the raw material IPA-copolymerized PBT is less than 4 mol%, the IPA copolymerization amount is likely to vary, which is not preferable.The lower limit of the IPA copolymerization amount of the raw material IPA-copolymerized PBT is more preferably 5 mol%. If the IPA copolymerization amount of the starting IPA-copolymerized PBT exceeds 35 mol%, the starting IPA-copolymerized PBT will have poor thermal stability and will be susceptible to decomposition and oxidative degradation while waiting in a polycondensation reaction tank during the production of the finished IPA-copolymerized PBT, which is undesirable. The upper limit of the IPA copolymerization amount of the starting IPA-copolymerized PBT is more preferably 30 mol%, even more preferably 25 mol%, particularly preferably 23 mol%, and most preferably 20 mol% or less.

[0034] <IPA copolymerized PBT of the present invention> The IPA copolymerized PBT of the present invention, that is, the produced IPA copolymerized PBT, has an IPA copolymerization amount of 0.1 to 2.0 mol %. If the IPA copolymerization amount of the IPA copolymerized PBT falls within this range, a molded article having excellent fitability and hinge characteristics can be obtained. The lower limit of the amount of IPA copolymerized in the produced IPA-copolymerized PBT is preferably 0.2 mol % or more, more preferably 0.3 mol % or more, and even more preferably 0.4 mol % or more. The upper limit of the amount of IPA copolymerized in the produced IPA-copolymerized PBT is preferably 1.9 mol %, more preferably 1.80 mol %, even more preferably 1.7 mol %, and most preferably 1.5 mol %.

[0035] The IPA copolymer PBT of the present invention is produced by reacting a raw material IPA copolymer PBT with a reaction product of a dicarboxylic acid component mainly composed of DMT or TPA and a diol component mainly composed of BDO. In this case, it is preferable to use these so that the ratio of the raw material IPA copolymer PBT to the total of the raw material IPA copolymer PBT and the reaction product of DMT or TPA and BDO is 1 to 20 mass%. The mass of the reaction product of DMT or TPA and BDO is the mass obtained by calculating the moles of DMT or TPA charged using a unit molecular weight of 220. Here, by setting the proportion of the raw material IPA-copolymerized PBT to 1 to 20 mass %, the IPA-copolymerized PBT of the present invention having an IPA copolymerization amount of 0.1 to 2.0 mol % can be produced with high accuracy from the raw material IPA-copolymerized PBT having an IPA copolymerization amount of preferably 4 to 35 mol %. The lower limit of the proportion of the raw material IPA-copolymerized PBT is more preferably 2 mass%, even more preferably 3 mass%, particularly preferably 4 mass%, and most preferably 5 mass%, while the upper limit of the proportion of the raw material IPA-copolymerized PBT is more preferably 15 mass% or less, even more preferably 13 mass%, particularly preferably 10 mass%, and most preferably 8 mass%. If the proportion of the raw material IPA copolymerized PBT is less than the lower limit of 1 mass %, the effect of excellent interfitting may not be fully obtained, and if it exceeds 20 mass %, it is undesirable because it is susceptible to decomposition and oxidative degradation while waiting in the polycondensation reaction tank.

[0036] [Method for producing IPA copolymerized PBT of the present invention] Although there are no particular limitations on the method for producing the IPA copolymer PBT of the present invention by reacting a raw material IPA copolymer PBT with DMT or TPA and BDO, or a reaction product thereof, it is preferable to produce the raw material IPA copolymer PBT in a polycondensation reaction tank according to the method for producing an IPA copolymer PBT of the present invention, then withdraw only a portion of the raw material IPA copolymer PBT produced from the polycondensation reaction tank, and use the polycondensation reaction tank in which the remainder of the raw material IPA copolymer PBT remains to produce the IPA copolymer PBT of the present invention. More specifically, the IPA copolymer PBT of the present invention can be produced by adding a reaction product of a dicarboxylic acid component mainly composed of DMT or TPA and a diol component mainly composed of BDO to the polycondensation reaction tank in which the raw material IPA copolymer PBT remains, and further performing polycondensation. In this case, the dicarboxylic acid component mainly composed of DMT or TPA and the diol component mainly composed of BDO may be directly charged into the polycondensation reaction tank. However, specifically, it is preferable from the viewpoint of production that these components are subjected to an ester exchange reaction or an esterification reaction in a transesterification reaction tank or an esterification reaction tank upstream of the polycondensation reaction tank in order to form a low-molecular-weight homo-PBT oligomer, which is then charged into the polycondensation reaction tank.

[0037] The reason why a raw material IPA-copolymerized PBT having a relatively large amount of IPA copolymerized is produced and then an oligomer of DMT or TPA and BDO is reacted with this raw material IPA-copolymerized PBT in a polycondensation reaction tank is as follows. That is, when an IPA-copolymerized PBT having an IPA copolymerization amount of 0.1 to 2.0 mol % is produced by reacting DMT or TPA with BDO and IPA, the IPA copolymerization amount of the resulting IPA-copolymerized PBT varies, making it difficult to produce an IPA-copolymerized PBT having the desired IPA copolymerization amount. As described in Patent Document 1, simply mixing homo-PBT with IPA-copolymerized PBT having a relatively large IPA copolymerization amount results in poor mixing, making it impossible to obtain an IPA-copolymerized PBT with a low IPA copolymerization amount and stable performance. In contrast, according to the present invention, a starting IPA-copolymerized PBT having a relatively large IPA copolymerization amount is produced in advance, and this starting IPA-copolymerized PBT is then subjected to a polycondensation reaction with DMT or TPA and BDO, or an oligomer thereof, thereby reducing the IPA copolymerization amount and enabling stable production of an IPA-copolymerized PBT having the desired IPA copolymerization amount by precisely controlling the IPA copolymerization amount. Furthermore, in this case, by adding DMT or TPA and BDO or an oligomer thereof to a polycondensation reaction tank containing the raw material IPA-copolymerized PBT and carrying out polycondensation, it is possible to improve the working efficiency and increase the productivity.

[0038] A method for producing the raw material IPA copolymerized PBT will be described below, followed by a method for producing the IPA copolymerized PBT of the present invention using this raw material IPA copolymerized PBT.

[0039] [Manufacturing method of raw material IPA copolymer PBT] <Raw material dicarboxylic acid component, diol component, copolymer component> As mentioned above, IPA copolymerized PBT refers to a polymer having a structure in which a dicarboxylic acid component containing DMT or TPA and IPA and a diol containing BDO are ester-bonded, in which 50 mol % or more of the dicarboxylic acid component is composed of terephthalic acid or dimethyl terephthalate, and 50 mol % or more of the diol component is composed of BDO.

[0040] In the present invention, the dicarboxylic acid component includes dicarboxylic acids and dicarboxylic acid derivatives. The dicarboxylic acid components other than terephthalic acid or dimethyl terephthalate and isophthalic acid used as raw materials for producing IPA-copolymerized PBT are not particularly limited, and examples include aromatic dicarboxylic acids such as phthalic 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, as well as derivatives of these dicarboxylic acids. Examples of 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 or dimethyl terephthalate and isophthalic 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.

[0041] 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, dibutylene glycol, and polytetramethylene ether 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 chemical recycling or biomass.

[0042] In the present invention, one or more of the following may further be used as copolymerization components: hydroxycarboxylic acids such as lactic acid, glycolic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, 6-hydroxy-2-naphthalenecarboxylic acid, and p-β-hydroxyethoxybenzoic acid; monofunctional components such as stearyl alcohol, benzyl alcohol, stearic acid, benzoic acid, t-butylbenzoic acid, and benzoylbenzoic acid; and trifunctional or higher polyfunctional components such as tricarballylic acid, trimellitic acid, trimesic acid, pyromellitic acid, gallic acid, trimethylolethane, trimethylolpropane, glycerol, and pentaerythritol.

[0043] <Manufacturing method for raw material IPA copolymer PBT> The method for producing the raw material IPA copolymerized PBT is not particularly limited, and the production method may be continuous or batchwise. The raw material IPA copolymer PBT can be produced by a conventional method, for example, through a process in which a slurry prepared by mixing a dicarboxylic acid component mainly composed of TPA and a diol component mainly composed of BDO in a predetermined ratio under stirring, and a slurry prepared by mixing IPA and BDO in a predetermined ratio under stirring, are charged into an esterification reaction tank and heated under normal or reduced pressure to cause an esterification reaction to form an IPA copolymer PBT oligomer, and then the resulting oligomer is gradually reduced in pressure and heated to cause a melt polycondensation reaction to produce the IPA copolymer PBT. When dimethyl terephthalate is used, it is charged together with BDO. Separately, IPA and BDO are mixed under stirring in a specified ratio to form a slurry, which is charged into an ester exchange reactor and heated together to melt, after which ester exchange and esterification reactions are carried out to obtain oligomers.

[0044] An example of the process for producing an oligomer is a method in which an esterification reaction tank or a transesterification reaction tank is used, and the esterification reaction or transesterification reaction (the proportion of all carboxyl groups or ester groups in the raw dicarboxylic acid component that have reacted with the diol component to be esterified or transesterified) is carried out using a catalyst under normal or reduced pressure to obtain an oligomer, while removing water or methanol produced in the reaction and excess diol component from the system. Typically, the temperature of the esterification reaction or transesterification reaction is about 210 to 230° C., the pressure is about 10 to 133 kPa, and the reaction time is about 1 to 4 hours.

[0045] An example of the melt polycondensation step is a method in which a polycondensation reaction vessel is used, and the diol produced is distilled out of the system while heating under reduced pressure in the presence of a catalyst.

[0046] 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.

[0047] The polycondensation reaction tank may be a single tank or a multi-stage tank, but in order to suppress coloration and deterioration and to inhibit an increase in terminal groups such as vinyl groups, it is preferable to carry out the reaction in at least one reaction tank 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.

[0048] The IPA copolymerized 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 or after water cooling into granular materials such as pellets or chips (for example, about 3 to 10 mm in length).

[0049] As will be described later, in producing the raw material IPA copolymerized PBT, only a portion of the IPA copolymerized PBT produced in this polycondensation reaction tank is extracted, and the remainder is left in the polycondensation reaction tank.The IPA copolymerized PBT remaining in the polycondensation reaction tank is used as the raw material IPA copolymerized PBT to produce the IPA copolymerized PBT of the present invention, as will be described later. In this case, the amount of IPA copolymerized PBT to be left in the polycondensation reaction tank is appropriately determined depending on the IPA copolymerization amount of the produced IPA copolymerized PBT (raw material IPA copolymerized PBT) and the IPA copolymerization amount of the target produced IPA copolymerized PBT.

[0050] <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, the IPA-copolymerized PBT finally obtained necessarily contains titanium and preferably a metal from Group 2A of the Periodic Table, and the amounts thereof will be described later.

[0051] 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.

[0052] In the case of a direct polymerization method using terephthalic acid, the titanium catalyst content in the raw IPA copolymer PBT and the IPA copolymer PBT of the present invention is preferably 5 to 100 ppm by mass of titanium atoms relative to the IPA copolymer 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. When dimethyl terephthalate is used, the titanium atom content is preferably 30 to 300 ppm, more preferably 50 to 200 ppm, in terms of mass ratio relative to the IPA copolymerized PBT. 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.

[0053] 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. Of these, magnesium acetate is preferred.

[0054] The content of Group 2A metal in the raw material IPA-copolymerized PBT and the IPA-copolymerized PBT of the present invention is not particularly limited, but is preferably 3 to 150 ppm by mass of Group 2A metal atoms relative to the IPA-copolymerized PBT. This amount is more preferably 5 ppm or more, and even more preferably 10 ppm or more. This amount is more preferably 50 ppm or less, even more preferably 40 ppm or less, particularly preferably 30 ppm or less, and most preferably 15 ppm or less. If the content of Group 2A metal is too high, color tone and hydrolysis resistance will deteriorate, while if it is too low, polymerization will deteriorate. When an acetate salt of a Group 2A metal is used, the acetic acid source will enter the reaction system, so the amount of Group 2A metal in the IPA-copolymerized PBT is preferably 15 ppm or less.

[0055] The molar ratio of titanium atoms to Group 2A metal atoms of the periodic table (Group 2A metal / titanium) contained in the raw material IPA copolymerized PBT and the IPA copolymerized PBT of the present invention is usually 0.01 to 100, preferably 0.1 to 10, more preferably 0.3 to 3, and even more preferably 0.3 to 1.5.

[0056] The content of metals such as titanium atoms in IPA copolymerized PBT can be measured using methods such as atomic emission, atomic absorption, and inductively coupled plasma (ICP) after recovering the metals in the polymer using a method such as wet ashing.

[0057] In producing the raw material IPA copolymer PBT and the IPA copolymer PBT of the present invention, in addition to the titanium compound and the Group 2A metal compound of the periodic table, reaction aids such as antimony compounds such as antimony trioxide, germanium compounds such as germanium dioxide and germanium tetroxide, manganese compounds, zinc compounds, zirconium compounds, cobalt compounds, phosphorus compounds such as orthophosphoric acid, phosphorous acid, hypophosphorous acid, polyphosphoric acid, esters or metal salts thereof, sodium hydroxide, sodium benzoate, etc. may be used.

[0058] [Method of producing IPA copolymerized PBT of the present invention] An oligomer obtained in advance by subjecting a dicarboxylic acid component containing DMT or TPA as a main component and a diol component containing BDO as a main component to an esterification or transesterification reaction is added to a polycondensation reaction tank containing the raw material IPA-copolymerized PBT produced as described above, and further polycondensation is carried out to obtain the IPA-copolymerized PBT of the present invention. In this case, the polycondensation reaction conditions and catalyst can be the same as those used in producing the starting IPA-copolymerized PBT.

[0059] When the IPA copolymer PBT of the present invention is produced by adding an oligomer to a polycondensation reaction tank in which the raw material IPA copolymer PBT remains and further performing polycondensation, it is preferable that the oligomer to be added has the above-mentioned esterification reaction rate or transesterification reaction rate of about 90 to 99%, from the viewpoint of the polycondensation reactivity of the raw material IPA copolymer PBT and the oligomer.

[0060] As described above, the amounts of DMT or TPA and BDO used in producing the IPA-copolymerized PBT of the present invention are such that the starting IPA-copolymerized PBT accounts for 1 to 20% by mass of the total of the starting IPA-copolymerized PBT and the reaction product of DMT or TPA and BDO, and the lower limit of the ratio of the starting IPA-copolymerized PBT is more preferably 2% by mass, even more preferably 3% by mass, particularly preferably 4% by mass, and most preferably 5% by mass.On the other hand, the upper limit is more preferably 15% by mass, even more preferably 13% by mass, particularly preferably 10% by mass, and most preferably 8% by mass. If this proportion is less than 1% by mass, the interlocking effect may not be sufficient, and if it exceeds 20% by mass, it is susceptible to decomposition and oxidative deterioration while waiting in the reaction vessel, which is undesirable. As described above, the mass of the reaction product of DMT or TPA and BDO is the mass obtained by calculating the amount of DMT or TPA charged based on a unit molecular weight of 220.

[0061] [Properties of IPA copolymerized PBT] When the IPA copolymer PBT of the present invention is used for compounding or injection molding, the intrinsic viscosity of the IPA copolymer 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, resulting in poor flowability and poor moldability. The intrinsic viscosity of the IPA copolymer 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.

[0062] Furthermore, when the IPA copolymerized PBT pellets of the present invention are used for extrusion applications such as film, sheet, or filament, the intrinsic viscosity of the IPA copolymerized 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, 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.

[0063] The intrinsic viscosity of the IPA-copolymerized PBT can be determined by the method described in the Examples section below.

[0064] From the viewpoint of molding cycle characteristics, the temperature-lowering crystallization temperature of the IPA copolymerized PBT of the present invention is preferably 160°C or higher, more preferably 162°C or higher. In the present invention, the temperature-decreasing crystallization temperature is a value measured with a differential scanning calorimeter at a temperature-decreasing rate of 20°C / min, and is the temperature of an exothermic peak due to crystallization that appears when the IPA-copolymerized PBT in a molten state is cooled at a temperature-decreasing rate of 20°C / min using the differential scanning calorimeter. The crystallization temperature during cooling corresponds to the crystallization rate, and the higher the crystallization temperature, the faster the crystallization rate. If the crystallization temperature during cooling is 160°C or higher, the cooling time during injection molding can be shortened, thereby increasing productivity. If the crystallization temperature during cooling is lower than 160°C, crystallization during injection molding takes a long time, necessitating a longer cooling time after injection molding, which may lengthen the molding cycle and reduce productivity. As described above, molding cycle characteristics can be evaluated by injection molding under certain molding conditions, and by the ease of demolding of the resulting molded product and the presence or absence of ejector pin marks. As the cooling and crystallization rate slows, ejector pin marks tend to form, and if the rate becomes even slower, demolding becomes impossible. Therefore, the cooling crystallization temperature can be used as an index of molding cycle characteristics.

[0065] [Compounding] The IPA copolymerized PBT of the present invention can be made into a compound product by adding various additives or compounding materials as required during or after the production of the IPA copolymerized PBT.

[0066] For example, antioxidants such as phenol compounds such as 2,6-di-t-butyl-4-octylphenol and pentaerythrityl tetrakis[3-(3',5'-t-butyl-4'-hydroxyphenyl)propionate], thioether compounds such as dilauryl-3,3'-thiodipropionate and pentaerythrityl tetrakis(3-laurylthiodipropionate), and phosphorus compounds such as triphenyl phosphite, tris(nonylphenyl)phosphite, and tris(2,4-di-t-butylphenyl)phosphite may be added, and release agents such as paraffin wax, microcrystalline wax, polyethylene wax, long-chain fatty acids and esters thereof, typified by montanic acid and montanic acid esters, and silicone oil may be added.

[0067] Furthermore, the IPA copolymer PBT of the present invention can be blended with a reinforcing filler. The reinforcing filler is not particularly limited, but examples include inorganic fibers such as glass fiber, carbon fiber, silica-alumina fiber, zirconia fiber, boron fiber, boron nitride fiber, potassium silicon nitride titanate fiber, and metal fiber, as well as organic fibers such as aromatic polyamide fiber and fluororesin fiber. Two or more of these reinforcing fillers can also be used in combination. Among the above reinforcing fillers, inorganic fillers, particularly glass fiber, are preferably used.

[0068] When the reinforcing filler is an inorganic fiber or an organic fiber, the average fiber diameter is not particularly limited, but is usually 1 to 100 μm, preferably 2 to 50 μm, more preferably 3 to 30 μm, and particularly preferably 5 to 20 μm. The average fiber length is not particularly limited, but is usually 0.1 to 20 mm, and preferably 1 to 10 mm.

[0069] The reinforcing filler is preferably surface-treated with a sizing agent or surface treatment agent to improve interfacial adhesion with the IPA copolymer PBT. Examples of sizing agents or surface treatment agents include functional compounds such as epoxy compounds, acrylic compounds, isocyanate compounds, silane compounds, and titanate compounds. The reinforcing filler can be surface-treated in advance with a sizing agent or surface treatment agent, or the reinforcing filler can be surface-treated by adding a sizing agent or surface treatment agent during preparation of the IPA copolymer PBT composition. The amount of reinforcing filler added is typically 150 parts by mass or less, preferably 5 to 100 parts by mass, per 100 parts by mass of the IPA copolymer PBT.

[0070] The IPA copolymer PBT of the present invention can be blended with other fillers in addition to the reinforcing filler. Examples of other fillers that can be blended include plate-like inorganic fillers, ceramic beads, asbestos, wollastonite, talc, clay, mica, zeolite, kaolin, potassium titanate, barium sulfate, titanium oxide, silicon oxide, aluminum oxide, and magnesium hydroxide. These can also be used in combination of two or more. Blending a plate-like inorganic filler can reduce the anisotropy and warpage of the resulting molded product. Examples of plate-like inorganic fillers include glass flakes, mica, and metal foil. Among these, glass flakes are preferred.

[0071] The IPA copolymerized PBT of the present invention can also be blended with a flame retardant to impart flame retardancy. Flame retardants are not particularly limited and include, for example, organic halogen compounds, antimony compounds, phosphorus compounds, other organic flame retardants, and inorganic flame retardants. Examples of organic halogen compounds include brominated polycarbonate, brominated epoxy resin, brominated phenoxy resin, brominated polyphenylene ether resin, brominated polystyrene resin, brominated bisphenol A, and polypentabromobenzyl acrylate. Examples of antimony compounds include antimony trioxide, antimony pentoxide, and sodium antimonate. Examples of phosphorus compounds include phosphate esters, polyphosphoric acid, ammonium polyphosphate, and red phosphorus. Examples of other organic flame retardants include nitrogen compounds such as melamine and cyanuric acid. Examples of other inorganic flame retardants include aluminum hydroxide, magnesium hydroxide, silicon compounds, and boron compounds. These compounds can also be used in combination of two or more.

[0072] The IPA copolymerized PBT of the present invention may contain other conventional additives, if necessary. Such additives are not particularly limited and include stabilizers such as antioxidants and heat stabilizers, as well as lubricants, mold release agents, catalyst deactivators, crystal nucleating agents, and crystallization accelerators. These additives can be added during or after polymerization. Furthermore, to impart desired properties to the IPA copolymerized PBT, stabilizers such as ultraviolet absorbers and weathering stabilizers, colorants such as dyes and pigments, antistatic agents, foaming agents, plasticizers, impact modifiers, and the like can be added.

[0073] The IPA copolymer PBT of the present invention can be blended with thermoplastic resins such as polyethylene, polypropylene, polystyrene, polyacrylonitrile, polymethacrylic acid ester, ABS resin, polycarbonate, polyamide, polyphenylene sulfide, polyethylene terephthalate, liquid crystal polyester, polyacetal, polyphenylene oxide, etc., and thermosetting resins such as phenolic resin, melamine resin, silicone resin, epoxy resin, etc. These thermoplastic resins and thermosetting resins can also be used in combination of two or more.

[0074] The method for blending the various additives and additional components such as resins is not particularly limited, but a method of melt-kneading the IPA-copolymerized PBT pellets using a single- or twin-screw extruder equipped with a vent for devolatilization is preferred. The components, including the additional components, can be fed to the kneader all at once, or sequentially. Alternatively, two or more components selected from the components, including the additional components, can be premixed.

[0075] When the IPA-copolymerized PBT of the present invention is used as at least a part of the raw materials and melt-kneaded in an extruder as described above to produce the compound product of the present invention, the kneading resin temperature in the extruder is preferably 350°C or lower. If the kneading resin temperature is 350°C or lower, thermal decomposition tends to be suppressed. From this viewpoint, the kneading resin temperature in the extruder is more preferably 310°C or lower, and even more preferably 300°C or lower. On the other hand, from the viewpoint of ensuring uniform meltability, the kneading resin temperature in the extruder is preferably 240°C or higher, particularly 250°C or higher. [Example]

[0076] 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.

[0077] (1) Reaction rate of IPA copolymerized PBT oligomer Esterification reaction rate It was calculated from the acid value and saponification value using the following formula. The acid value was determined by dissolving the oligomer in dimethylformamide and titrating it with a 0.1 N KOH / methanol solution. The saponification value was determined by hydrolyzing the oligomer with a 0.5N KOH / ethanol solution and titrating it with 0.5N hydrochloric acid. Esterification rate (%) = ((saponification value - acid value) / saponification value) x 100 Transesterification rate Approximately 100 mg of oligomer was dissolved in 1 mL of a mixed solvent of deuterated chloroform / hexafluoroisopropanol = 7 / 3 (volume ratio), and 36 μL of deuterated pyridine was added. 1 H-NMR was measured to determine the amount of terminal methoxycarbonyl groups (equivalents / ton). The NMR device used was an "AL-400" manufactured by JEOL Ltd. The transesterification rate was calculated using the following formula. Transesterification rate (%) = 100 - (amount of terminal methoxycarbonyl groups / 9081) x 100

[0078] (2) Intrinsic viscosity (IV) 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.)

[0079] (3) Titanium and Group 2A metal concentrations IPA copolymerized 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).

[0080] (4) IPA copolymerization amount The sample was dissolved in a mixed solvent of deuterated chloroform / hexafluoroisopropanol (7 / 3 mass ratio) containing a trace amount of tetramethylsilane, and then deuterated pyridine was added and the sample was transferred to an NMR sample tube. 1 H NMR spectra were measured. The actual copolymerization amount of IPA is preferably within ±10%, more preferably within ±7%, even more preferably within ±5%, and most preferably within ±3% of the target copolymerization amount.

[0081] (5) Molding cycle characteristics The molding cycle characteristics were judged using the cooling crystallization temperature, with a cooling crystallization temperature of 160°C or higher being rated as "usable (◯)" and a temperature below 160°C being rated as "unusable (×)". The produced IPA copolymerized PBT pellets were used in a PerkinElmer differential scanning calorimeter (Model DSC7), which was heated from room temperature to 300°C at a heating rate of 20°C / min, and then cooled to 80°C at a cooling rate of 20°C / min. The endothermic peak temperature was taken as the melting point, and the exothermic peak temperature was taken as the cooling crystallization temperature.

[0082] (6) Evaluation of fit Using the IPA copolymerized PBT obtained in each example and comparative example, male connectors and female connectors were molded under the following conditions using a FUNAC FAS-150B injection molding machine and a multi-cavity mold with eight cavities per shot as shown in Figure 1. Cylinder temperature: 260~270℃ Mold temperature: 30℃ Thereafter, the specimen was treated at 80°C for 24 hours to allow post-shrinkage, and then the mating properties of the male connector and the female connector were evaluated. To evaluate the fitability, a fit test was conducted on 48 pairs (8 pairs x 6 times) of the cavity numbers shown in Figure 1 using the combinations shown in Table 1 below.

[0083] [Table 1]

[0084] Fitting was judged on a four-point scale from good to bad: ◎ → ○ → △ → ×, and the following points were assigned to each group. The total score for each group was used as the overall evaluation score. For example, if all were ◎, the score would be 5 × 48 = 240 points. The higher the overall evaluation score, the better the fit is judged to be. ◎:5 points 〇:3 points △:2 points ×: 0 points

[0085] (7) Hinge characteristic test Using the IPA copolymerized PBT obtained in each example and comparative example, hinged test specimens of the size and shape shown in Figure 1(a) (plan view), Figure 1(b) (side view), and Figure 1(c) (enlarged side view of hinge portion A in Figure 1(b)) were molded using a mold attached to a FUNAC50B injection molding machine. In Figures 1(a) to 1(c), 1 and 2 indicate the main body of the molded article, 3 indicates the hinge portion, and G indicates the gate. The dimensions of the test specimens are in millimeters. The molding conditions were as follows: Cylinder temperature: 245℃ Mold temperature: 50℃ Injection pressure: 86MPa Injection speed: 120mm / sec Injection time: 6 seconds Cooling time: 7 seconds Test: The hinged test piece obtained by the above method was bent 180 degrees at the hinge, as shown in the enlarged side view in Figure 1(d), and the appearance of the hinge after bending was visually observed from the direction of the arrow and rated on a five-point scale as shown below. In the following, "turned up" means that the part of the hinge after bending that was visually observed had local cracks or peeling, making the surface uneven. The hinge property test was carried out on five test pieces at 23°C, and the appearance evaluation results were scored on a five-point scale. The total score of the five test pieces was used as the overall score. The higher the overall score, the better the hinge property was judged to be. 10 points: No abnormalities at all 5 points: Partial peeling is observed 3 points: Peeling is observed on the entire surface 2 points: Some cracks are observed 0 points: Cracks are observed

[0086] [1,4-butanediol] [Example of biomass-derived 1,4-butanediol production] <Production Example 1: 1,4-Butanediol by Hydrogenation of Biomass-Derived Succinic Acid Ester> BDO manufactured by Yuanli Chemical Group and BDO manufactured by Zhejiang Boju New Materials Co., Ltd. were mixed to obtain a mixed liquid. The resulting mixed liquid 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 resulting main fraction was extracted and analyzed by gas chromatography, and the 1,4-butanediol content was found to be 99% by mass or more. This main fraction was used as biomass-derived 1,4-butanediol.

[0087] [Example of chemically recycled 1,4-butanediol production] <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 mass % or more. This main fraction was used as chemically recycled 1,4-butanediol.

[0088] [Dimethyl terephthalate] [Example of chemically recycled dimethyl terephthalate production] <Production Example 3: Chemically recycled dimethyl terephthalate 1> 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.

[0089] <Production Example 4: Chemically Recycled Dimethyl Terephthalate 2> 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 a cake. The obtained cake 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 (chemically recycled dimethyl terephthalate 2) was extracted and analyzed by gas chromatography, revealing that the dimethyl terephthalate content was 99% by mass or more.

[0090] <Production Example 5: Chemically Recycled Dimethyl Terephthalate 3> 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 the oil bath. The temperature and pressure of the oil bath were controlled while monitoring the distillate, and the light-boiling components containing tetrahydrofuran, the initial fraction, the main fraction, and the bottoms were obtained in the order of distillation. A portion of the obtained main fraction (chemically recycled dimethyl terephthalate 3) was extracted and analyzed by gas chromatography, and it was found that the content of dimethyl terephthalate was 99 mass % or more.

[0091] [Terephthalic acid] [Example of chemically recycled terephthalic acid production] <Production Example 6: Chemically Recycled Terephthalic Acid 1> In the same manner as in Production Example 3, a white solid of dimethyl terephthalate (chemically recycled dimethyl terephthalate 1) having a dimethyl terephthalate content of 99% by mass or more was obtained. The resulting white solid of 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 (chemically recycled terephthalic acid 1) was analyzed by liquid chromatography, and the terephthalic acid content was found to be 99% by mass or more.

[0092] <Production Example 7: Chemically Recycled Terephthalic Acid 2> A main fraction having a dimethyl terephthalate content of 99% by mass or more was obtained in the same manner as in Production Example 4. This main fraction of dimethyl terephthalate (chemically recycled dimethyl terephthalate 2) was used instead of the white solid dimethyl terephthalate, and hydrolysis and purification were carried out in the same manner as in Production Example 6 to obtain chemically recycled terephthalic acid 2 as a white solid having a terephthalic acid content of 99% by mass or more.

[0093] <Production Example 8: Chemically Recycled Terephthalic Acid 3> In the same manner as in Production Example 5, a main fraction containing 99% by mass or more of dimethyl terephthalate was obtained. Instead of the white solid dimethyl terephthalate, 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 6, to obtain chemically recycled terephthalic acid 3 as a white solid having a terephthalic acid content of 99% by mass or more.

[0094] [Example 1] IPA copolymerized PBT was produced as follows. A clean transesterification reactor, free of any residue, was charged with 838.3 parts by mass of petrochemical-derived DMT (manufactured by SK Petrochemical) and 466.8 parts by mass of petrochemical-derived BDO (manufactured by Mitsubishi Chemical Corporation) to yield 1,000 parts by mass of polymer. 37.8 parts by mass of petrochemical-derived IPA (manufactured by Mitsubishi Gas Chemical Company, Inc.) was added as a slurry mixed with 36.9 parts by mass (1.80 moles) of petrochemical-derived BDO (manufactured by Mitsubishi Chemical Corporation). Tetrabutyl titanate was added as a catalyst in the form of a BDO solution to yield 61 ppm by mass of the resulting polymer (IPA copolymerized PBT) in terms of titanium metal. The liquid temperature in the reactor was then maintained at 150°C for 60 minutes, after which it was increased to 210°C over 90 minutes and maintained at 210°C for 30 minutes. The transesterification reaction was carried out for a total of 180 minutes, during which the resulting methanol was distilled off.

[0095] Fifteen minutes before the end of the transesterification reaction, magnesium acetate tetrahydrate was dissolved in BDO and added to the resulting polymer at 48 ppm by mass as magnesium metal. Furthermore, 1.06 parts by mass of a hindered phenol antioxidant (ADEKA Corporation, AO-60: pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] was added in the form of a BDO slurry. Subsequently, tetrabutyl titanate was added as a BDO solution in an amount that would result in 33 ppm by mass of titanium metal relative to the resulting polymer. The resulting mixture was then transferred to a clean, residue-free polycondensation reactor equipped with a stirrer, nitrogen inlet, heater, thermometer, distillation tube, and vacuum exhaust port, and the polycondensation reaction was carried out under reduced pressure.

[0096] The polycondensation reaction was carried out by gradually reducing the pressure in the tank from normal pressure to 0.4 KPa over 85 minutes and continuing at 0.4 KPa or less. The reaction temperature was maintained at 210°C for 15 minutes from the start of pressure reduction, and then increased to 240°C over 45 minutes and maintained at this temperature. The reaction was terminated when the specified stirring torque was reached. The polycondensation reaction took 150 minutes.

[0097] The pressure in the vessel was then restored from the reduced pressure state with nitrogen, and then pressurized for polymer discharge. The temperature of the heat medium in the die during discharge was set to 235°C, and the polymer was extruded from the die in the form of strands. The strands were then cooled in a cooling water tank, cut with a strand cutter, and pelletized. When 90% of 1,000 parts by mass of polymer had been withdrawn from the polycondensation reactor, withdrawal was stopped. 100 parts by mass of IPA-copolymerized PBT remained in the polycondensation reactor. The proportion of IPA in the polymer was 5.0 mol %. In other words, the amount of IPA copolymerized in the raw material IPA-copolymerized PBT was 5 mol %.

[0098] Next, 442.4 parts by mass of BDO was added to 794.4 parts by mass of dimethyl terephthalate (Table 2) in the transesterification reaction tank. This resulted in 900 parts by mass of homo-PBT. Subsequently, similar to the method described above, a transesterification reaction and a polycondensation reaction were carried out in the polycondensation reaction tank where the raw material IPA-copolymerized PBT remained. The transesterification reaction rate of the oligomer obtained in the transesterification reaction (oligomer charged into the polycondensation reaction tank) was 95%. The polymer was then extruded from the die head in the form of a strand and cut with a rotary cutter to obtain IPA-copolymerized PBT pellets (major axis approximately 3 mm, minor axis approximately 2 mm, length approximately 4 mm). The intrinsic viscosity (IV) of the resulting IPA-copolymerized PBT was 0.85 dL / g. The proportion of IPA in the polymer was 0.5 mol%, i.e., the amount of IPA copolymerized was 0.5 mol%. The evaluation results of the obtained IPA copolymerized PBT are summarized in Table 2.

[0099] [Example 2] In a clean transesterification reactor free of residues, 706.2 parts by mass of petrochemical-derived DMT (manufactured by SK Petrochemical) and 393.3 parts by mass of petrochemical-derived BDO (manufactured by Mitsubishi Chemical Corporation) were added to make 1000 parts by mass of polymer. The transesterification reaction was carried out in the same manner as in Example 1, except that 150.9 parts by mass of petrochemical-derived IPA (manufactured by Mitsubishi Gas Chemical Company, Inc.) was added as a slurry mixed with 147.5 parts by mass (1.80 moles) of petroleum-derived BDO (manufactured by Mitsubishi Chemical Corporation). Subsequently, IPA copolymerized PBT was obtained and 95% was extracted according to the details shown in Table 2. The amount of IPA copolymerized in the extracted IPA copolymerized PBT was 20 mol %. Thereafter, using the IPA copolymerized PBT remaining in the polycondensation reaction tank as the raw IPA copolymerized PBT, 467.0 parts by mass of BDO was added to 838.5 parts by mass of dimethyl terephthalate (Table 2) in a transesterification reaction tank. This resulted in 950 parts by mass of homo-PBT. Subsequently, similar to the method described above, a transesterification reaction and a polycondensation reaction were carried out in the polycondensation reaction tank containing the remaining raw IPA copolymerized PBT. The transesterification reaction rate of the oligomer obtained in the transesterification reaction (oligomer introduced into the polycondensation reaction tank) was 95%. Subsequently, a produced IPA copolymerized PBT was obtained in the same manner as in Example 1. The produced IPA copolymerized PBT had an intrinsic viscosity (IV) of 0.85 dL / g and an IPA copolymerization amount of 1.0 mol %. The evaluation results of the obtained IPA copolymerized PBT are summarized in Table 2.

[0100] [Example 3] In a clean transesterification reactor free of residues, 618.0 parts by mass of petrochemical-derived DMT (manufactured by SK Petrochemical) and 344.2 parts by mass of petrochemical-derived BDO (manufactured by Mitsubishi Chemical Corporation) were added to make 1000 parts by mass of polymer. The transesterification reaction was carried out in the same manner as in Example 1, except that 226.3 parts by mass of petrochemical-derived IPA (manufactured by Mitsubishi Gas Chemical Company, Inc.) was added as a slurry mixed with 221.1 parts by mass (1.80 moles) of petroleum-derived BDO (manufactured by Mitsubishi Chemical Corporation). Subsequently, IPA copolymerized PBT was obtained and 95% was extracted according to the details shown in Table 2. The amount of IPA copolymerized in the extracted IPA copolymerized PBT was 30.0 mol %. Subsequently, 467.0 parts by mass of BDO was added to 838.5 parts by mass of dimethyl terephthalate shown in Table 2 in the transesterification reaction tank. This resulted in 950 parts by mass of homo-PBT. Subsequently, transesterification reaction and polycondensation reaction were carried out in the same manner as described above. The transesterification reaction rate of the oligomer obtained in the transesterification reaction (oligomer charged into the polycondensation reaction tank) was 95%. Subsequently, the same procedure as in Example 1 was carried out to obtain IPA-copolymerized PBT. The intrinsic viscosity (IV) of the produced IPA-copolymerized PBT was 0.85 dL / g, and the amount of IPA copolymerized was 1.5 mol %. The evaluation results of the obtained IPA copolymerized PBT are summarized in Table 2.

[0101] [Examples 4 to 14] A raw material IPA-copolymerized PBT was produced in the same manner as in Example 2, except that the raw materials were changed as shown in Table 2, and then a production IPA-copolymerized PBT was produced. The evaluation results of the obtained IPA copolymerized PBT are summarized in Table 2.

[0102] [Example 15] A slurry of 603.3 parts by mass of petroleum-derived terephthalic acid (manufactured by Toray Industries, Inc.) and 589.5 parts by mass (1.80 molar ratio) of petroleum-derived BDO (manufactured by Mitsubishi Chemical Corporation) was added to a clean esterification reactor free of residues, resulting in 1,000 parts by mass of polymer. Next, 458.2 parts by mass (1.40 molar ratio) of the same BDO was added. Petroleum-derived IPA (manufactured by Mitsubishi Gas Chemical Company, Inc.) was mixed with 147.5 parts by mass (1.80 molar ratio) of petroleum-derived BDO (manufactured by Mitsubishi Chemical Corporation) to form a slurry, which was then added. The esterification reaction vessel was charged with a BDO solution containing a tetrabutyl titanate catalyst in an amount that would result in 40 ppm titanium in the IPA copolymerized PBT. The liquid temperature in the vessel was raised from 150°C to 220°C over 90 minutes and held at 220°C for 60 minutes. During this time, the generated water was distilled off, and the esterification reaction was carried out for a total of 180 minutes. Fifteen minutes before the end of the esterification reaction, magnesium acetate tetrahydrate was dissolved in BDO and added so that the magnesium metal was 10 ppm by mass relative to the polymer produced. The mixture was then transferred to a clean, residue-free polycondensation reactor equipped with a stirrer, nitrogen inlet, heater, thermometer, distillation tube, and vacuum exhaust port, and the polycondensation reaction was carried out under reduced pressure.

[0103] The polycondensation reaction was carried out by gradually reducing the pressure in the tank from normal pressure to 0.4 KPa over 85 minutes and then maintaining it at 0.4 KPa or less. The reaction temperature was maintained at 220°C for 15 minutes from the start of pressure reduction, and then increased to 240°C over 45 minutes and maintained at this temperature. The reaction was terminated when the specified stirring torque was reached. The polycondensation reaction took 150 minutes.

[0104] The inside of the polycondensation reactor was then restored to pressure with nitrogen, and then pressurized for polymer discharge. The temperature of the heat medium in the die during discharge was set to 235°C, and the polymer was extruded from the die in the form of a strand. The strand was then cooled in a cooling water tank, cut with a strand cutter, and pelletized. When 95% of 1000 parts by mass of the polymer had been withdrawn from the polycondensation reactor, withdrawal was stopped. 50 parts by mass of IPA-copolymerized PBT remained in the polycondensation reactor. The proportion of IPA in the polymer was 20.0 mol%. In other words, the amount of IPA copolymerized in the raw material IPA-copolymerized PBT was 20 mol%.

[0105] Next, a slurry containing 717 parts by mass of petroleum-derived terephthalic acid and 700.7 parts by mass (1.80 molar ratio) of petroleum-derived BDO (manufactured by Mitsubishi Chemical Corporation) was added to the esterification reactor. Next, 545.0 parts by mass (1.40 molar ratio) of the same BDO was added. This resulted in 950 parts by mass of homo-PBT. Similar to the method described above, an esterification reaction and a polycondensation reaction were carried out in the polycondensation reactor containing the remaining raw material IPA-copolymerized PBT. The esterification reaction rate of the oligomer obtained in the esterification reaction (the oligomer introduced into the polycondensation reactor) was 96%. The resulting strand was then extruded from the die head and cut with a rotary cutter to obtain IPA-copolymerized 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 proportion of IPA in the polymer was 1.0 mol%, i.e., the amount of IPA copolymerized in the produced IPA-copolymerized PBT was 1.0 mol%. The evaluation results of the obtained IPA copolymerized PBT are summarized in Table 3.

[0106] [Examples 16 to 26] An IPA-copolymerized PBT was produced in the same manner as in Example 15, except that the raw materials were changed as shown in Table 3. The evaluation results of the obtained IPA copolymerized PBT are summarized in Table 3.

[0107] [Comparative Example 1] To a clean transesterification reactor free of residue, 882.7 parts by mass of petrochemical-derived DMT (manufactured by SK Petrochemical) and 491.6 parts by mass of petrochemical-derived BDO (manufactured by Mitsubishi Chemical Corporation) were added so as to give a polymer total of 1000 parts by mass. Thereafter, transesterification and polycondensation reactions were carried out to obtain homo-PBT in the same manner as in Example 1. The intrinsic viscosity (IV) of the obtained homo-PBT was 0.85 dL / g. The evaluation results of the obtained homo-PBT are summarized in Table 3.

[0108] Comparative Example 2 Five parts by mass of the raw material IPA copolymerized PBT with 20 mol% IPA copolymerization obtained in Example 2 and 95 parts by mass of the homo-PBT obtained in Comparative Example 1 were charged into a blender and mixed uniformly to prepare a mixture. The resulting mixture was melt-kneaded at 260°C using a vented twin-screw extruder with a screw diameter of 30 mm (TEX30C, manufactured by The Japan Steel Works, Ltd.), extruded into strands, and pelletized. The evaluation results of the obtained IPA copolymerized PBT composition are summarized in Table 3.

[0109] In Tables 2 and 3, "residual residue carried in" in the production method column indicates a production method in which an oligomer is further added to the raw material IPA copolymerized PBT remaining in the polycondensation reaction tank. In addition, in the column for the produced IPA copolymerized PBT, the "target IPA copolymerization amount" is the IPA copolymerization amount calculated from the amount of raw material charged, the "analyzed IPA copolymerization amount" is the IPA copolymerization amount determined by analyzing the produced IPA copolymerized PBT, and the "actual / charged ratio" is the ratio (percentage) of the analyzed IPA copolymerization amount to the target IPA copolymerization amount. In Tables 2 and 3, in the columns for the origin of DMT, TPA, BDO, and IPA, "petroleum-derived" is written as "petroleum-derived," "biomass-derived" as "bio," and "chemically recycled" as "CR."

[0110] [Table 2]

[0111] [Table 3]

[0112] From Tables 2 and 3, it can be seen that the IPA copolymerized PBT of the present invention has excellent molding cycle characteristics, stable and excellent hinge characteristics, and high fitability. Furthermore, it is clear that the method for producing IPA copolymerized PBT of the present invention makes it possible to produce the targeted IPA copolymerized PBT having a low IPA copolymerization amount with good precision. Furthermore, this effect is not limited to when petroleum-derived dimethyl terephthalate or petroleum-derived terephthalic acid is used as dimethyl terephthalate or terephthalic acid, but can also be obtained when chemically recycled dimethyl terephthalate or chemically recycled terephthalic acid is used. It can also be seen that the effect can be obtained not only when petroleum-derived BDO is used, but also when biomass-derived BDO or chemically recycled BDO is used. In contrast, Comparative Example 1 using homo PBT and Comparative Example 2 using a compound of IPA copolymerized PBT and homo PBT are inferior in fitability and hinge properties. [Explanation of symbols]

[0113] 1,2 Molded product body 3 Hinge part G Gate< / ipa> < / bdo>

Claims

1. an isophthalic acid copolymerized polybutylene terephthalate obtained by copolymerizing isophthalic acid; a reaction product of dimethyl terephthalate or terephthalic acid with 1,4-butanediol; is reacted with An isophthalic acid copolymerized polybutylene terephthalate composition having an isophthalic acid copolymerization amount of 0.1 to 2.0 mol %.

2. The isophthalic acid-copolymerized polybutylene terephthalate composition according to claim 1, wherein the amount of the isophthalic acid-copolymerized polybutylene terephthalate used is 1 to 20 mass% based on the total amount of the isophthalic acid-copolymerized polybutylene terephthalate and dimethyl terephthalate or the reaction product of terephthalic acid and 1,4-butanediol.

3. The isophthalic acid-co-polybutylene terephthalate composition according to claim 1 or 2, wherein the dimethyl terephthalate is derived from petroleum, chemical recycling, or biomass.

4. The isophthalic acid copolymerized polybutylene terephthalate composition according to claim 1 or 2, wherein the terephthalic acid is derived from petroleum, chemical recycling, or biomass.

5. The isophthalic acid copolymerized polybutylene terephthalate composition according to claim 1 or 2, wherein the 1,4-butanediol is derived from petroleum, chemical recycling, or biomass.

6. The isophthalic acid copolymerized polybutylene terephthalate composition according to claim 1 or 2, wherein the isophthalic acid is derived from petroleum, chemical recycling, or biomass.

7. A method for producing an isophthalic acid-copolymerized polybutylene terephthalate composition, comprising producing isophthalic acid-copolymerized polybutylene terephthalate in a polycondensation reaction tank, extracting a portion of the isophthalic acid-copolymerized polybutylene terephthalate produced from the polycondensation reaction tank, and using the polycondensation reaction tank in which the remainder of the isophthalic acid-copolymerized polybutylene terephthalate remains to produce the isophthalic acid-copolymerized polybutylene terephthalate composition.

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