Polybutylene terephthalate and molded article

Abstract

To provide polybutylene terephthalate that exhibits a low dielectric loss tangent in the high-frequency range, and allows the ratio to a frequency equal to or lower than 50 GHz to remain at or under a prescribed value even at an especially high frequency exceeding 50 GHz.SOLUTION: There is provided a polybutylene terephthalate having a terminal ester group, where an intrinsic viscosity (IV) of the polybutylene terephthalate is 0.7-1.3 dL / g, and for a dried test piece having a moisture content of 100 ppm or less, obtained by molding the polybutylene terephthalate, a dielectric loss tangent (DDF60) at a frequency of 60 GHz measured at 23°C by a cylindrical cavity resonator perturbation method is 0.003-0.0055; a ratio (DDF60 / DDF5) of the dielectric loss tangent (DDF60) at a frequency of 60 GHz to a dielectric loss tangent (DDF5) at a frequency of 5 GHz is 0.8-1.20; and a terminal vinyl group concentration is 3-20 equivalents / ton.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to polybutylene terephthalate (hereinafter sometimes abbreviated as "PBT") and a PBT composition, a molded article formed therefrom, and its uses.

Background Art

[0002] PBT using terephthalic acid (hereinafter sometimes abbreviated as "TPA") or dimethyl terephthalate (hereinafter sometimes abbreviated as "DMT") as the main component of the dicarboxylic acid component and 1,4-butanediol (hereinafter sometimes abbreviated as "BDO") as the main component of the diol component has excellent mechanical properties, heat resistance, moldability, and recyclability, and also has high mechanical strength and excellent chemical resistance. Therefore, it is widely used as a material for industrial molded articles such as connectors, relays, and switches for automobiles and electric / electronic devices. In recent years, PBT has come to be used even under severe conditions of high temperature and high humidity. However, in such applications, conventional PBT is likely to generate tetrahydrofuran. Particularly under conditions where there are electrical contacts in the vicinity, problems such as the generated gas being carbonized and adhered due to arc discharge, resulting in abnormal conduction of the contacts, occur. Furthermore, in recent years, materials with reduced relative permittivity and dielectric loss tangent have been demanded for applications to high-frequency transmission components such as portable communication terminals and automotive millimeter-wave sensors based on high-speed communication standards using high frequencies in the 1 GHz band or higher. In the materials for high-frequency transmission components, particularly when the dielectric loss tangent is high, when a high-frequency signal comes into contact with the material, the high frequency is converted into heat, resulting in a phenomenon where communication accuracy such as communication distance decreases due to a decrease in signal strength, which has become a problem.

[0003] Conventionally, as a method for reducing generated gas, Patent Document 1 describes that by substituting the terminals of PBT with a monofunctional compound having a carboxyl group or a hydroxyl group and making the amount of carboxyl group terminals and the amount of terminal hydroxyl groups below specific values, the generation of organic gas during molding and use can be reduced. However, although this measure is effective in suppressing tetrahydrofuran generated by the decomposition of the hydroxyl terminus, its practical effect is not sufficient due to the remaining components used for end-capping. In particular, when adding components used for end-capping after polymerization, such as compounds, it led to unfavorable results. On the other hand, when adding the components used for end-capping at the melt polymerization stage, although the remaining amount is small, the necessary ends for the polymerization reaction are also capped, resulting in problems such as not reaching the desired degree of polymerization in melt polymerization or poor polymerization reactivity.

[0004] On the other hand, as low-dielectric polyesters with improved dielectric properties of thermoplastic polyester resins, the following (1) and (2) have been proposed. (1) A low-dielectric polyester having an intrinsic viscosity of 0.3 to 1.2 dl / g obtained by copolymerizing an acid component containing terephthalic acid and / or a terephthalic acid derivative with a diol component containing 2,2-alkyl-substituted-1,3-propanediol (Patent Document 2) (2) A low-dielectric tangent polyester obtained from an acid component containing terephthalic acid and / or a terephthalic acid derivative and a diol component containing 1,4-butanediol (Patent Documents 3 and 4) In these low-dielectric polyesters, the terminal hydroxyl groups are blocked with monofunctional end-capping compounds or acid anhydrides, and as a result, the hydroxyl ends that deteriorate the dielectric performance in the high-frequency band are reduced.

[0005] As described above, PBT is produced using a dicarboxylic acid component containing TPA or DMT as a main component and a diol component containing BDO as a main component. Regarding the production method of the raw material BDO, in recent years, in addition to the conventional production method of BDO using fossil fuels such as petroleum (referred to as "petrochemical-derived" in the present invention), methods for producing biomass-derived BDO (referred to as "biomass-derived" in the present invention) using biomass resources as raw materials have also been developed. For example, a method of obtaining BDO by hydrogenating succinic acid obtained by the fermentation method of sugar (for example, Patent Document 5) and a method of directly obtaining BDO by fermenting biomass resources such as sugar (for example, Patent Document 6) are known. In addition, chemically recycled BDO produced by depolymerizing polybutylene terephthalate by a chemical recycling method has also been proposed (for example, Patent Document 7).

[0006] Regarding terephthalic acid as well, in recent years, in addition to the conventional production method of petrochemical-derived terephthalic acid using fossil fuels such as petroleum as raw materials, methods for producing biomass-derived terephthalic acid using biomass resources as raw materials 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 by dehydration dimerization of isobutanol (for example, Patent Document 8). Dimethyl terephthalate can be easily obtained from the terephthalic acid obtained by this method according to a conventional method. In addition, chemically recycled dimethyl terephthalate recovered by a chemical recycling method by depolymerizing waste polyester has also been proposed (for example, Patent Documents 9 and 10).

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

[0008] Although the low-dielectric polyester disclosed in Patent Document 2 has an effect of reducing the relative permittivity in a low-frequency band of 1 MHz or less, there is a problem that the dielectric loss tangent in a high-frequency band is insufficient. Although the low-dielectric polyesters disclosed in Patent Documents 3 and 4 have an effect of reducing the relative permittivity and the dielectric loss tangent, it is necessary to react a monofunctional carboxylic acid compound, an acid anhydride, or a monofunctional hydroxy compound with the terminal groups of the polyester. When the addition amount is large, the terminals necessary for the polymerization reaction are also blocked, so that the desired degree of polymerization cannot be reached by melt polymerization, or the polymerization reactivity deteriorates, and the degree of polymerization of PBT is impaired. Also, when the addition amount is large, there is a problem that the added components do not all react with the terminals of the polyester and remain in the polymer.

[0009] Furthermore, generally when the molecular weight is large, the total number of terminal groups becomes small. That is, the hydroxy terminals that deteriorate the dielectric performance in the high-frequency band are reduced. However, due to the high molecular weight, the fluidity during melting is poor and the moldability is not favorable. Furthermore, in the case of a high frequency exceeding 50 GHz, the dielectric loss tangent becomes high, which is not favorable. That is, in the prior art, there were problems such as insufficient dielectric loss tangent in the high-frequency band, inability to obtain the desired intrinsic viscosity, poor fluidity during melting due to high molecular weight, and inferior moldability. Furthermore, there were also problems such as deterioration of the dielectric loss tangent at particularly high frequencies exceeding 50 GHz.

[0010] On the other hand, as described above, regarding the raw material BDO of PBT, in addition to petrochemical-derived BDO, in recent years, biomass-derived BDO and chemical recycled BDO have been proposed. However, in the conventional method, for applying PBT using biomass-derived BDO or chemical recycled BDO to high-frequency transmission components, no consideration has been given to reducing the dielectric loss tangent in the high-frequency band. Similarly, regarding terephthalic acid and dimethyl terephthalate, in the conventional method, for applying PBT using biomass-derived terephthalic acid or dimethyl terephthalate or chemical recycled terephthalic acid or dimethyl terephthalate to high-frequency transmission components, no consideration has been given to reducing the dielectric loss tangent in the high-frequency band.

[0011] In view of the above prior art, an object of the present invention is to provide polybutylene terephthalate having a desired intrinsic viscosity, a small dielectric loss tangent in the high-frequency band, and a ratio to a frequency below 50 GHz that is not more than a predetermined value even in a particularly high frequency band exceeding 50 GHz. Furthermore, an object of the present invention is to provide polybutylene terephthalate that can sufficiently obtain the above effects even when using biomass-derived BDO or chemical recycled BDO as the raw material BDO. Similarly, an object of the present invention is to provide polybutylene terephthalate that can sufficiently obtain the above effects even when using biomass-derived or chemical recycled terephthalic acid or dimethyl terephthalate as the raw material terephthalic acid component. Another object of the present invention is to provide polybutylene terephthalate, its composition, and its molded articles that can be suitably used for sheets, films, monofilaments, fibers, electrical and electronic components, automotive components, and the like.

Means for Solving the Problem

[0012] The inventor of the present invention repeated studies as follows to solve the above problems and obtained the following findings. When the terminal carboxyl groups of PBT are blocked with monofunctional hydroxyl groups, the amount of terminal carboxyl groups decreases. However, when the remaining terminal hydroxyl groups undergo a deglycolation reaction (de-BDO), even if the amount of terminal carboxyl groups is small, the molecular weight of PBT can be increased, and as a result, the terminal hydroxyl groups of PBT also decrease. Therefore, the terminal hydroxyl groups that deteriorate the dielectric properties in the high-frequency band can be reduced.

[0013] The inventor of the present invention examined Patent Document 1 and Patent Document 4. In Patent Document 1, the polymerization temperature is as high as 250°C, and the resulting PBT has a high terminal vinyl group concentration generated by the decomposition of the main chain and the decomposition of terminal hydroxyl groups, and the terminal hydroxyl group concentration is low. For this reason, an effect of lowering the dielectric tangent was found. However, it was found that the coloring of PBT due to decomposition was remarkable, which was not preferable in terms of PBT quality. On the other hand, in Patent Document 4, the polymerization temperature is as low as 245°C, and the terminal vinyl group concentration is very low. It was found that the effect on reducing the dielectric tangent derived from the terminal vinyl group concentration is small.

[0014] Based on these technical ideas, the inventor of the present invention further conducted studies and reached the following present invention. In addition, the above-described effects derived from these technical ideas are not at all suggested in Patent Document 1 and Patent Document 4.

[0015] [1] Polybutylene terephthalate having terminal ester groups, The intrinsic viscosity (IV) of the polybutylene terephthalate is 0.7 to 1.3 dL / g, The dielectric tangent (DDF) at a frequency of 60 GHz measured by the following method 60) is from 0.003 to 0.0055, and the ratio (DDF 60 ) of the dielectric loss tangent at a frequency of 60 GHz (DDF 60 ) to the dielectric loss tangent at a frequency of 5 GHz (DDF5) is from 0.9 to 1.20, A polybutylene terephthalate characterized in that the terminal vinyl group concentration is from 3 to 20 equivalents / ton. <Method for measuring dielectric loss tangent> For a dried test piece with a water content of 100 ppm or less obtained by molding the polybutylene terephthalate, the dielectric loss tangent is measured at a predetermined frequency under a temperature condition of 23 °C by the cylindrical cavity resonator perturbation method.

[0016] [2] A polybutylene terephthalate having terminal ester groups, wherein the intrinsic viscosity (IV) of the polybutylene terephthalate is from 0.7 to 1.3 dL / g, the dielectric loss tangent at a frequency of 80 GHz (DDF 80 ) measured by the following method is from 0.003 to 0.006, and the ratio (DDF 80 ) of the dielectric loss tangent at a frequency of 80 GHz (DDF 80 ) to the dielectric loss tangent at a frequency of 5 GHz (DDF5) is from 0.95 to 1.29, A polybutylene terephthalate characterized in that the terminal vinyl group concentration is from 3 to 20 equivalents / ton. <Method for measuring dielectric loss tangent> For a dried test piece with a water content of 100 ppm or less obtained by molding the polybutylene terephthalate, the dielectric loss tangent is measured at a predetermined frequency under a temperature condition of 23 °C by the cylindrical cavity resonator perturbation method.

[0017] [3] A polybutylene terephthalate having terminal ester groups, wherein the intrinsic viscosity (IV) of the polybutylene terephthalate is from 0.7 to 1.3 dL / g, the dielectric loss tangent at a frequency of 60 GHz (DDF 60 ) measured by the following method is from 0.003 to 0.0055, and the dielectric loss tangent at a frequency of 1.1 GHz (DDF 1.1) is from 0.003 to 0.005, and the ratio (DDF 1.1 ) of the dielectric loss tangent at a frequency of 1.1 GHz (DDF 1.1 ) to the dielectric loss tangent at a frequency of 5 GHz (DDF5) is from 0.9 to 1.2, A polybutylene terephthalate characterized in that the terminal vinyl group concentration is from 3 to 20 equivalents / ton. <Method for measuring dielectric loss tangent> For a dried test piece with a moisture content of 100 ppm or less obtained by molding the polybutylene terephthalate, the dielectric loss tangent is measured at a predetermined frequency under temperature conditions of 23°C by the cylindrical cavity resonator perturbation method.

[0018] [4] A polybutylene terephthalate having terminal ester groups, wherein the intrinsic viscosity (IV) of the polybutylene terephthalate is from 0.7 to 1.3 dL / g, The dielectric loss tangent at a frequency of 60 GHz (DDF 60 ) measured by the following method is from 0.003 to 0.0055, the dielectric loss tangent at a frequency of 2.5 GHz (DDF 2.5 ) is from 0.003 to 0.005, and the ratio (DDF 2.5 ) of the dielectric loss tangent at a frequency of 2.5 GHz (DDF 2.5 ) to the dielectric loss tangent at a frequency of 5 GHz (DDF5) is from 0.9 to 1.2, A polybutylene terephthalate characterized in that the terminal vinyl group concentration is from 3 to 20 equivalents / ton. <Method for measuring dielectric loss tangent> For a dried test piece with a moisture content of 100 ppm or less obtained by molding the polybutylene terephthalate, the dielectric loss tangent is measured at a predetermined frequency under temperature conditions of 23°C by the cylindrical cavity resonator perturbation method.

[0019] [5] A polybutylene terephthalate having terminal ester groups, wherein the intrinsic viscosity (IV) of the polybutylene terephthalate is from 0.7 to 1.3 dL / g, The dielectric loss tangent at a frequency of 60 GHz (DDF 60) is 0.003 to 0.0055, and the dielectric tangent (DDF 10 ) is 0.003 to 0.005, and the ratio (DDF 10 ) of the dielectric tangent (DDF 10 ) at a frequency of 10 GHz to the dielectric tangent (DDF5) at a frequency of 5 GHz is 0.9 to 1.2, A polybutylene terephthalate characterized in that the terminal vinyl group concentration is 3 to 20 equivalents / ton. <Method for measuring dielectric tangent> For a dry test piece with a water content of 100 ppm or less obtained by molding the polybutylene terephthalate, the dielectric tangent is measured at a predetermined frequency under a temperature condition of 23 °C by the cylindrical cavity resonator perturbation method.

[0020] [6] A polybutylene terephthalate having terminal ester groups, The intrinsic viscosity (IV) of the polybutylene terephthalate is 0.7 to 1.3 dL / g, The dielectric tangent (DDF 60 ) measured by the following method at a frequency of 60 GHz is 0.003 to 0.0055, and the dielectric tangent (DDF 20 ) at a frequency of 20 GHz is 0.003 to 0.005, and the ratio (DDF 20 ) of the dielectric tangent (DDF 20 ) at a frequency of 20 GHz to the dielectric tangent (DDF5) at a frequency of 5 GHz is 0.9 to 1.2, A polybutylene terephthalate characterized in that the terminal vinyl group concentration is 3 to 20 equivalents / ton. <Method for measuring dielectric tangent> For a dry test piece with a water content of 100 ppm or less obtained by molding the polybutylene terephthalate, the dielectric tangent is measured at a predetermined frequency under a temperature condition of 23 °C by the cylindrical cavity resonator perturbation method.

[0021] [7] A polybutylene terephthalate having terminal ester groups, The intrinsic viscosity (IV) of the polybutylene terephthalate is 0.7 to 1.3 dL / g, The dielectric dissipation factor (DDF 60 ) at a frequency of 60 GHz measured by the following method is 0.003 to 0.0055, the dielectric dissipation factor (DDF 28 ) at a frequency of 28 GHz is 0.003 to 0.005, and the ratio (DDF 28 ) of the dielectric dissipation factor (DDF 28 ) at a frequency of 28 GHz to the dielectric dissipation factor (DDF5) at a frequency of 5 GHz (DDF ) is 0.9 to 1.2, and the terminal vinyl group concentration is 3 to 20 equivalents / ton. <Method for measuring dielectric dissipation factor> For a dry test piece with a water content of 100 ppm or less obtained by molding the polybutylene terephthalate, the dielectric dissipation factor is measured at a predetermined frequency under a temperature condition of 23 °C by the cylindrical cavity resonator perturbation method.

[0022] [8] A polybutylene terephthalate having terminal ester groups, the intrinsic viscosity (IV) of the polybutylene terephthalate is 0.7 to 1.3 dL / g, the dielectric dissipation factor (DDF 60 ) at a frequency of 60 GHz measured by the following method is 0.003 to 0.0055, the dielectric dissipation factor (DDF 40 ) at a frequency of 40 GHz is 0.003 to 0.005, and the ratio (DDF 40 ) of the dielectric dissipation factor (DDF 40 ) at a frequency of 40 GHz to the dielectric dissipation factor (DDF5) at a frequency of 5 GHz (DDF ) is 0.9 to 1.2, and the terminal vinyl group concentration is 3 to 20 equivalents / ton. <Method for measuring dielectric dissipation factor> For a dry test piece with a water content of 100 ppm or less obtained by molding the polybutylene terephthalate, the dielectric dissipation factor is measured at a predetermined frequency under a temperature condition of 23 °C by the cylindrical cavity resonator perturbation method.

[0023] [9] The polybutylene terephthalate according to any one of [1] to [8], wherein the raw material 1,4-butanediol of the polybutylene terephthalate is 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 biomass resources, and 1,4-butanediol produced by depolymerization of polybutylene terephthalate.

[0024]

[10] The polybutylene terephthalate according to any one of [1] to [9], wherein the terephthalic acid component of the raw material of the polybutylene terephthalate contains any one of terephthalic acid or dimethyl terephthalate produced by chemical recycling of polyester, or terephthalic acid or dimethyl terephthalate produced using biomass resources.

[0025]

[11] A polybutylene terephthalate composition obtained by blending an additive and / or an inorganic filler with the polybutylene terephthalate according to any one of [1] to

[10] .

[12] A molded article obtained by melt-molding the polybutylene terephthalate according to any one of [1] to

[10] or a polybutylene terephthalate composition containing the polybutylene terephthalate.

[13] The molded article according to

[12] , which is used as a component for high-frequency transmission.

[14] A metal composite molded article in which the molded article according to

[12] or

[13] and a metal component are integrated.

Advantages of the Invention

[0026] The PBT of the present invention has a small dielectric loss tangent in the high-frequency band, and also has a small dielectric loss tangent even in a particularly high frequency band exceeding 50 GHz, and the ratio to the frequency below that is equal to or less than a predetermined value. Such an effect of the PBT of the present invention is also effectively exhibited in PBT using biomass-derived BDO or chemically recycled BDO as the raw material BDO. Similarly, it is also effectively exhibited in PBT using biomass-derived or chemically recycled terephthalic acid or dimethyl terephthalate as the raw material terephthalic acid and the raw material dimethyl terephthalate. Therefore, the PBT of the present invention and the molded article obtained from the PBT composition containing the same are used in the high-frequency band. It can be preferably used for various applications such as electric and electronic parts, automotive parts, films, sheets, filaments, and the like.

Mode for Carrying Out the Invention

[0027] Hereinafter, the present invention will be described in detail. However, the description of the constituent elements described below is a representative example of the embodiments of the present invention, and the present invention is not limited to these contents. In the present invention, the “main component” in the dicarboxylic acid component refers to a component contained in an amount of 50 mol% or more in the component. The same applies to the “main component” in the diol component. Also, “ppm” refers to “mass ppm”.

[0028] [Polybutylene terephthalate] The PBT of the present invention has a terminal ester group, an intrinsic viscosity (IV) of 0.7 to 1.3 dL / g, a terminal vinyl group concentration of 3 to 20 equivalents / ton, and a dielectric tangent and a dielectric tangent ratio at a predetermined frequency measured by the following method having predetermined values. <Method for Measuring Dielectric Tangent> For a dry test piece having a moisture content of 100 ppm or less obtained by molding the polybutylene terephthalate, the dielectric tangent is measured at a predetermined frequency under a temperature condition of 23° C. by the cylindrical cavity resonator perturbation method.

[0029] <Raw Material Dicarboxylic Acid Component, Diol Component, and Copolymerization Component> In the present invention, PBT refers to a polymer having a structure in which a terephthalic acid component and 1,4-butanediol (BDO) are ester-bonded, where 50 mol% or more of the dicarboxylic acid component consists of the terephthalic acid component and 50 mol% or more of the diol component consists of BDO. The proportion of the terephthalic acid component in all the dicarboxylic acid components is preferably 70 mol% or more, more preferably 80 mol% or more, and particularly preferably 95 mol% or more. The proportion of BDO in all the diol components is preferably 70 mol% or more, more preferably 80 mol% or more, and even more preferably 95 mol% or more. When the terephthalic acid component or BDO is less than 50 mol%, the crystallization rate of PBT decreases, leading to deterioration of moldability.

[0030] Here, the terephthalic acid component includes terephthalic acid and terephthalic acid derivatives, and the dicarboxylic acid component includes dicarboxylic acids and dicarboxylic acid derivatives.

[0031] (Terephthalic acid·dimethyl terephthalate) The raw material terephthalic acid (TPA) used in the present invention can be terephthalic acid synthesized by oxidation of paraxylene, a petrochemical product (petroleum-derived terephthalic acid), chemical recycled terephthalic acid obtained by recovering waste polyester and depolymerizing the recovered polyester, or biomass-derived terephthalic acid obtained using paraxylene produced from isobutanol or ethanol manufactured from plants such as corn and sugarcane as described in Patent Document 8 mentioned above. From the perspective of aiming for a sustainable society for the global environment and future generations, the terephthalic acid used in the present invention is preferably chemical recycled terephthalic acid. For example, as in Production Examples 6 to 8 described later, chemical recycled DMT can be hydrolyzed to produce terephthalic acid. Also, from the same perspective, the terephthalic acid used in the present invention is preferably biomass-derived terephthalic acid. In the present invention, TPA derived from each can be used, and two or more of these can be mixed and used.

[0032] As the raw material dimethyl terephthalate (DMT) used in the present invention, as the raw material terephthalic acid, terephthalic acid synthesized by oxidation of para-xylene, a petrochemical product (petroleum-derived terephthalic acid), recovered waste polyester, and chemical recycle terephthalic acid obtained by depolymerizing the recovered polyester can be used. As described in Patent Document 8 mentioned above, those using biomass-derived terephthalic acid obtained using para-xylene produced from plant-derived isobutanol or ethanol such as corn and sugarcane as raw materials can be used. That is, these terephthalic acids can be esterified with methanol under high-temperature and high-pressure conditions, and the esterification reaction mixture can be separated and purified to obtain DMT. From the perspective of aiming for a sustainable society for the global environment and future generations, the raw material terephthalic acid of DMT used in the present invention is preferably chemical recycle terephthalic acid. Also, from the same perspective, the raw material terephthalic acid of DMT used in the present invention is preferably biomass-derived terephthalic acid. DMT may be DMT directly produced by chemical recycling by depolymerization of polyesters such as polyethylene terephthalate or polybutylene terephthalate, as described in Patent Documents 9 and 10 mentioned above, specifically, as in Production Examples 3 to 5 described later. In the present invention, DMTs derived from each can be used, and two or more of these can be mixed and used.

[0033] (Other dicarboxylic acid components) There is no particular limitation on dicarboxylic acids other than terephthalic acid as raw materials for producing PBT. For example, 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, 2,6-naphthalenedicarboxylic acid; alicyclic dicarboxylic acids such as 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid; aliphatic dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, etc. can be mentioned. In addition, examples of dicarboxylic acid derivatives other than dimethyl terephthalate include esters of these dicarboxylic acids or terephthalic acid, and ester-forming derivatives such as dicarboxylic acid halides. These other dicarboxylic acid components may be used alone or in combination of two or more. Note that as the dicarboxylic acid component such as succinic acid, those derived from biomass may be used.

[0034] (1,4-butanediol) There is no particular limitation on the method for producing BDO used in the present invention. Examples of the method for producing BDO include the generally used Reppe method, allyl alcohol method, butadiene method, and the method of hydrogenating succinic acid. On the other hand, as described above, in recent years, in addition to those derived from petrochemicals, biomass-derived BDO using biomass resources as raw materials has also been developed. For example, as in the aforementioned Patent Document 5, there is biomass-derived BDO produced by hydrogenating succinic acid or a succinic acid derivative obtained by a direct fermentation method or a fermentation method of sugar, such as succinic anhydride, dialkyl succinate (more specifically, dialkyl succinate having an alkyl group with 1 to 4 carbon atoms, preferably 1 to 3 carbon atoms, more preferably 1 to 2 carbon atoms, and most preferably a methyl group having 1 carbon atom). Also, as in the aforementioned Patent Document 6, BDO directly produced by fermenting biomass resources such as sugar is also known. In addition, like the aforementioned Patent Document 7, chemical recycling BDO obtained by depolymerizing PBT has also been developed. As the raw material BDO for the polybutylene terephthalate of the present invention, BDO by the succinic acid reduction method as in Production Example 1 described later may be used, or chemical recycling BDO as in Production Example 2 may be used. The BDO used in the present invention may be a mixture of two or more different BDOs derived therefrom. In any of the manufacturing methods of BDO, it is preferable to perform distillation purification and hydrogenation purification as necessary in each step.

[0035] (Other diol components) In the present invention, there are no particular restrictions on the diol components other than BDO. For example, 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-cyclohexanedimethanol, and 1,4-cyclohexanedimethanol; aromatic diols such as xylylene glycol, 4,4'-dihydroxybiphenyl, 2,2-bis(4-hydroxyphenyl)propane, and bis(4-hydroxyphenyl)sulfone can be mentioned. Regarding these diol components other than BDO, those derived from biomass or chemical recycling may also be used. Regarding these diol components other than BDO, only one kind may be used, or two or more kinds may be mixed and used.

[0036] (Copolymerization component) In the present invention, for the production of PBT, further, hydroxycarboxylic acids such as lactic acid, glycolic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic 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.

[0037] In particular, the PBT of the present invention having a terminal ester group is PBT in which a compound having a monofunctional hydroxyl group is bonded to the terminal carboxyl group of PBT. As its production raw material, it is preferable to use a compound having a monofunctional hydroxyl group for introducing a terminal ester group. The compound having a monofunctional hydroxyl group will be described later.

[0038] <Terminal group concentration> The terminal hydroxyl group concentration, terminal ester group concentration, terminal carboxyl group concentration, and terminal vinyl group concentration of PBT described below can be determined by the method described in the Examples section shown later.

[0039] (Terminal hydroxyl group concentration) The terminal hydroxyl group concentration of the PBT of the present invention is usually 50 equivalents / ton or less, preferably 40 equivalents / ton or less, more preferably 30 equivalents / ton, and particularly preferably 20 equivalents / ton or less. When the terminal hydroxyl group concentration is too high, the amount of tetrahydrofuran (THF) generated by the decomposition of the terminal hydroxyl group during melting such as molding increases. For example, under conditions where there are electrical contacts in the vicinity, this gas may carbonize and adhere due to arc discharge, causing problems such as abnormal conduction of the contacts. In addition, THF is generated during molding, and appearance defects derived from THF such as silver appear in the molded product, which is not preferable. Moreover, since the dielectric loss tangent also deteriorates, it is not preferable. There is no particular limitation on the lower limit of the terminal hydroxyl group concentration, but it is usually 10 equivalents / ton or more.

[0040] (Terminal ester group concentration) From the viewpoint of reducing the dielectric loss tangent, the terminal ester group concentration of the PBT of the present invention is preferably 10 equivalents / ton or more. The terminal ester group concentration is more preferably 15 equivalents / ton or more, and still more preferably 20 equivalents / ton or more in terms of further reducing the dielectric loss tangent. On the other hand, when the terminal ester group concentration is too high, the polymerization reactivity deteriorates and the desired degree of polymerization cannot be obtained. Therefore, the terminal ester group concentration is preferably 50 equivalents / ton or less.

[0041] (Terminal carboxyl group concentration) The terminal carboxyl group concentration of the PBT of the present invention is usually 0.1 to 50 equivalents / ton, preferably 1 to 40 equivalents / ton, more preferably 5 to 30 equivalents / ton, particularly preferably 7 to 25 equivalents / ton, and most preferably 10 to 19 equivalents / ton. When the terminal carboxyl group concentration is too high, the hydrolysis resistance may deteriorate. In order to make this value less than 0.1 equivalents / ton, for example, extremely small production scales have to be adopted, which is economically disadvantageous and not practical.

[0042] (Terminal vinyl group concentration) The terminal vinyl group concentration of the PBT of the present invention is usually 3 equivalents / ton or more, preferably 5 equivalents / ton or more, more preferably 7 equivalents / ton in terms of further reducing the dielectric loss tangent. On the other hand, the upper limit of the terminal vinyl group concentration is usually 20 equivalents / ton, preferably 18 equivalents / ton or less, more preferably 16 equivalents / ton or less, still more preferably 13 equivalents / ton or less, and particularly preferably 10 equivalents / ton or less. If the terminal vinyl group concentration is too high, it will cause deterioration of the color tone. Also, since the terminal vinyl group does not undergo a condensation reaction, it is not preferable even when the degree of polymerization is increased.

[0043] The terminal vinyl group is generated by thermal decomposition, not by hydrolysis of the ester bond. Therefore, the polymerization temperature during PBT production affects the generation of the terminal vinyl group. Generally, in batch polymerization, the temperature is changed from the low temperature side to the high temperature side. Since the terminal vinyl group is significantly affected by the highest temperature in the system, temperature control of the polymerization temperature is important. To achieve both the terminal vinyl group and the color tone, it is preferable to control the polymerization temperature at a temperature exceeding 245 °C and less than 250 °C. The terminal vinyl group concentration can be adjusted not only by the polymerization temperature but also by the molar ratio of the raw material BDO and the raw material terephthalic acid component, the degree of vacuum during polymerization, and the amount of catalyst. That is, the larger the molar ratio of the raw material BDO and the raw material terephthalic acid component, the more the terminal vinyl group tends to increase. When the final pressure during polymerization is higher than 0.133 kPa, the terminal vinyl group tends to increase. The smaller the amount of catalyst, the more the terminal vinyl group tends to increase.

[0044] <Concentration of monofunctional component> The monofunctional component is a compound having a monofunctional hydroxyl group as a terminal capping agent present in the process of producing the PBT of the present invention and remaining without forming an ester bond with the terminal group of the PBT. The "monofunctional component" contained in the PBT of the present invention can be measured by the method for measuring the concentration of the monofunctional component in the PBT described in the Examples section below. In this case, for the reactant (such as an ester compound etc.) of the compound (such as methanol etc.) used for the measurement and the monofunctional component, it is also included as a monofunctional component, and the monofunctional component before the reaction is added to the monofunctional component concentration. Also, for the ester compound of the monofunctional component and the raw material compound in the PBT of the present invention, it is included as a monofunctional component, and the monofunctional component before the esterification reaction is added to the monofunctional component concentration. In addition, the monofunctional component according to the present invention, in the measurement by the method for measuring the concentration of the monofunctional component in PBT described in the examples section below, after dissolving PBT in hexafluoroisopropanol which is a good solvent for PBT, when adding methanol which is a poor solvent for PBT, it does not precipitate, and also includes the monofunctional component and / or the monofunctional component reactant in the components dissolved in the solution.

[0045] In addition, when the PBT of the present invention contains a monofunctional component, it is called a "PBT composition", but the concentration of the monofunctional component in the PBT of the present invention is, as described later, very small, for example, it also includes a range almost equivalent to the content of catalytic metal components such as Ti used in the production of PBT and contained in the produced PBT. Therefore, in the present invention, the PBT composition containing PBT and the monofunctional component is also called "PBT".

[0046] The concentration of the monofunctional component of the PBT of the present invention is preferably 20 to 2000 ppm (mass ppm), more preferably 25 to 1800 ppm, and still more preferably 30 to 1600 ppm. When the concentration of the monofunctional component is too low, the dielectric loss tangent becomes high, and also the desired intrinsic viscosity cannot be obtained. Conversely, when the concentration of the monofunctional component is too high, when used as a molded product, under conditions where there is an electrical contact in the vicinity, the monofunctional component is carbonized and adhered due to arc discharge, causing abnormal conduction of the contact, and also, due to the influence of the polar monofunctional component, it is likely to absorb moisture in the environment during use, and there are problems such as the dielectric loss tangent being in an unfavorable range.

[0047] <Intrinsic viscosity> The intrinsic viscosity (IV) of the PBT of the present invention is 0.7 to 1.3 dL / g. When the intrinsic viscosity is less than 0.7 dL / g, the mechanical strength of the obtained molded product becomes insufficient. When it exceeds 1.3 dL / g, the melt viscosity increases, the fluidity deteriorates, and the moldability tends to deteriorate. The intrinsic viscosity of the PBT of the present invention is preferably 0.72 to 1.26 dL / g, more preferably 0.75 to 1.20 dL / g. The intrinsic viscosity (IV) of PBT can be determined by the method described in the Examples section below.

[0048] <Dielectric properties> (Dielectric tangent) The PBT of the present invention is characterized in that the dielectric tangent measured at 23°C by the cylindrical cavity resonator perturbation method for a dry test piece with 100 ppm or less of moisture obtained by molding the PBT shows the following values according to each measurement frequency. That is, the dielectric tangent (DDF 1.1 ) at a frequency of 1.1 GHz is usually 0.003 to 0.005, preferably 0.0035 to 0.0045. The dielectric tangent (DDF 2.5 ) at a frequency of 2.5 GHz is usually 0.003 to 0.005, preferably 0.0035 to 0.0049. The dielectric tangent (DDF5) at a frequency of 5 GHz is usually 0.003 to 0.005, preferably 0.0035 to 0.0049. The dielectric tangent (DDF 10 ) at a frequency of 10 GHz is usually 0.003 to 0.005, preferably 0.0035 to 0.0049. The dielectric tangent (DDF 20 ) at a frequency of 20 GHz is usually 0.003 to 0.005, preferably 0.0035 to 0.0049. The dielectric tangent (DDF 28 ) at a frequency of 28 GHz is usually 0.003 to 0.005, preferably 0.0035 to 0.0049. The dielectric tangent (DDF 40) is usually 0.003 to 0.005, preferably 0.0035 to 0.0049. The dielectric loss tangent (DDF 60 ) at a frequency of 60 GHz is usually 0.003 to 0.0055, preferably 0.0035 to 0.0054. The dielectric loss tangent (DDF 80 ) at a frequency of 80 GHz is usually 0.003 to 0.006, preferably 0.0035 to 0.0059.

[0049] If the dielectric loss tangent at each frequency is below the above upper limit, the dielectric loss can be reduced, the degradation of the high-frequency signal can be suppressed, so it is excellent in antenna gain, radar accuracy, etc., and is preferably used for various high-frequency transmission components. Specifically, it can be preferably used for the following high-frequency transmission components.

[0050] (Ratio of dielectric loss tangents) The PBT of the present invention is such that the ratio of the dielectric loss tangents measured for each frequency at 23 °C by the cylindrical cavity resonator perturbation method for a dry test piece with a moisture content of 100 ppm or less obtained by molding the PBT satisfies the following values. The ratio of the dielectric loss tangent at a frequency of 60 GHz to the dielectric loss tangent at a frequency of 5 GHz (DDF 60 / DDF5) is usually 0.9 to 1.20, preferably 0.90 to 1.17, more preferably 1.03 to 1.15. The ratio of the dielectric loss tangent at a frequency of 80 GHz to the dielectric loss tangent at a frequency of 5 GHz (DDF 80 / DDF5) is usually 0.95 to 1.29, preferably 0.97 to 1.20, more preferably 1.03 to 1.15. The ratio of the dielectric loss tangent at a frequency of 1.1 GHz to the dielectric loss tangent at a frequency of 5 GHz (DDF 1.1 / DDF5) is usually 0.9 to 1.2, preferably 0.90 to 1.17, more preferably 1.03 to 1.15. The ratio of the dielectric loss tangent at a frequency of 2.5 GHz to the dielectric loss tangent at a frequency of 5 GHz (DDF 2.5The ratio (DDF5) of the dielectric tangent at a frequency of 10 GHz to the dielectric tangent at a frequency of 5 GHz is generally 0.9 to 1.2, preferably 0.90 to 1.17, and more preferably 1.03 to 1.15. The ratio (DDF5) of the dielectric tangent at a frequency of 10 GHz to the dielectric tangent at a frequency of 5 GHz 10 The ratio (DDF5) of the dielectric tangent at a frequency of 10 GHz to the dielectric tangent at a frequency of 5 GHz is generally 0.9 to 1.2, preferably 0.90 to 1.17, and more preferably 1.03 to 1.15. The ratio (DDF5) of the dielectric tangent at a frequency of 20 GHz to the dielectric tangent at a frequency of 5 GHz 20 The ratio (DDF5) of the dielectric tangent at a frequency of 20 GHz to the dielectric tangent at a frequency of 5 GHz is generally 0.9 to 1.2, preferably 0.90 to 1.17, and more preferably 1.03 to 1.15. The ratio (DDF5) of the dielectric tangent at a frequency of 28 GHz to the dielectric tangent at a frequency of 5 GHz 28 The ratio (DDF5) of the dielectric tangent at a frequency of 28 GHz to the dielectric tangent at a frequency of 5 GHz is generally 0.9 to 1.2, preferably 0.90 to 1.17, and more preferably 1.03 to 1.15. The ratio (DDF5) of the dielectric tangent at a frequency of 40 GHz to the dielectric tangent at a frequency of 5 GHz 40 The ratio (DDF5) of the dielectric tangent at a frequency of 40 GHz to the dielectric tangent at a frequency of 5 GHz is generally 0.9 to 1.2, preferably 0.90 to 1.17, and more preferably 1.03 to 1.15. When these ratios are within the above ranges, they can be preferably used for various applications using high frequencies.

[0051] Frequencies of 1.1 GHz and its vicinity are used in GPS (Global Positioning System) etc., and are suitably used for those components. Frequencies of 2.5 GHz and its vicinity are used in Bluetooth, a wireless communication technology often used when short - range devices communicate with each other, microwave ovens, wireless LAN (Local area network), etc., and are suitably used for those components. Frequencies of 5 GHz and its vicinity are used in ETC (Electronic Toll Collection System), wireless LAN (Local area network), etc., and are suitably used for those components. Frequencies of 10 GHz and its vicinity are used in, for example, relay of TV program materials by broadcasters and radars for speed measurement, and are suitably used for those components. Frequencies of 20 GHz and its vicinity are used in, for example, millimeter-wave radars that assume autonomous driving for automobiles and can detect distant objects even in complex situations such as when there are large reflectors nearby like billboards, and are suitably used for those components. Frequencies of 28 GHz and its vicinity are used in, for example, 5G (fifth-generation mobile communication system) of mobile phones, and are suitably used for those components. Frequencies of 40 GHz and its vicinity are used in, for example, satellite communications, and are suitably used for those components. Frequencies of 60 GHz and its vicinity are used in, for example, ultra-high-speed digital wireless communication WPAN (wireless Personal Area Network), and are suitably used for those components. Frequencies of 80 GHz and its vicinity are used in, for example, millimeter-wave radars that assume autonomous driving for automobiles, have excellent angular resolution and range resolution, and can perform high-precision obstacle detection, and are suitably used for those components.

[0052] The dielectric tangent of PBT is obtained from S-parameter methods such as the free-space S-parameter method and the corrugated circular waveguide S-parameter method, and cavity resonance methods such as the balanced disk resonator method, the Fabry-Perot open resonator method, the split cylinder cavity resonator method, the split post dielectric resonator method, and the cylindrical cavity resonator perturbation method. However, from the viewpoint of the accuracy of the measured values, in the present invention, it is defined by the value obtained by the cylindrical cavity resonator perturbation method.

[0053] <Relative permittivity> For the PBT of the present invention, for a dry test piece with a water content of 100 ppm or less obtained by molding the PBT, the relative permittivity measured at 23°C by the cylindrical cavity resonator perturbation method is preferably 3.0 or less, and more preferably 2.9 or less, at any of the above frequencies in terms of being able to reduce the transmission loss due to high-frequency reflection on the surface of the molded product.

[0054] [Method for Producing Polybutylene Terephthalate] The method for producing PBT of the present invention will be described below. In the production of PBT of the present invention, an aromatic dicarboxylic acid or its ester-forming derivative and a diol are subjected to an esterification reaction or a transesterification reaction by a known polycondensation method, and then a polycondensation reaction is carried out. When producing PBT, it can be produced by adding a terminal capping agent serving as a terminal ester group introducing agent at any stage of the esterification reaction, the transesterification reaction, or the polycondensation reaction. In the method for producing PBT, as a method for obtaining the required intrinsic viscosity, there are only melt polymerization and a method of solid-phase polymerization after melt polymerization. A method of performing only melt polymerization is preferable in order to obtain cost, simplicity of operation, and stable quality.

[0055] The diol component such as raw material BDO and the dicarboxylic acid component such as terephthalic acid component are as described above.

[0056] The production form when producing PBT of the present invention may be a continuous type or a batch type.

[0057] The terminal ester group introducing agent, that is, the terminal capping agent, is a compound that can react with the carboxyl group of the residue of the raw material diol or its ester-forming derivative to form a terminal ester group, and examples thereof include monofunctional hydroxy compounds.

[0058] The monofunctional compound having a hydroxyl group as a terminal capping agent for substituting the terminal of the carboxyl group of PBT is not particularly limited. However, in the case of a compound having a low molecular weight, it is likely to volatilize and flow out of the system without being introduced into the polymer terminal due to the temperature, reduced pressure conditions, etc. during PBT production. Therefore, the monofunctional compound is preferably a compound having 7 or more carbon atoms. Examples of particularly preferred compounds include high molecular weight alcohol compounds such as phenoxybenzyl alcohol, diphenoxybenzyl alcohol, octadecanol, 2-hexyl-1-dodecanol, 2-decyl-1-tetradecanol, 2-dodecyl-1-hexadecanol, and 2-tetradecyloctadecane-1-ol. These end-capping agents may be used alone or in combination of two or more.

[0059] The amount of these end-capping agents used is not particularly limited as long as it can produce PBT that satisfies the suitable terminal ester group concentration of the PBT of the present invention and the above-described dielectric loss tangent. However, it is preferably 0.2 to 3.5 mol% based on the raw material terephthalic acid component, more preferably 0.3 to 3.2 mol%, and even more preferably 0.5 to 3.0 mol%.

[0060] When the molar ratio of carboxylic acid derivatives such as BDO / dimethyl terephthalate or the molar ratio of carboxylic acids such as BDO / terephthalic acid used in the reaction is large, the number of terminal hydroxyl groups during the esterification reaction or transesterification reaction increases. Also, the deglycolization reaction increases and the reaction becomes slower. From this perspective, in the production of PBT of the present invention, when using a carboxylic acid derivative such as dimethyl terephthalate as a raw material, the molar ratio of the carboxylic acid derivative such as BDO / dimethyl terephthalate used in the reaction is preferably 1.3 or less, particularly preferably 1.2 or less. The lower limit of this ratio is usually 1, but preferably 1.13 or more. On the other hand, when using terephthalic acid, the molar ratio of the carboxylic acid such as BDO / terephthalic acid used in the reaction is larger compared to the case of using a carboxylic acid derivative such as dimethyl terephthalate, and is preferably 2.6 or less, particularly preferably 2.0 or less, especially preferably 1.6 or less. This is to prevent BDO from changing to THF due to the influence of terephthalic acid, resulting in a substantial decrease in the molar ratio and making the reaction difficult to proceed or not react. However, if this molar ratio is too high, THF will be generated in excess, which is not preferable. The lower limit of this ratio is usually 1, but preferably 1.13 or more.

[0061] (Polycondensation catalyst) When polycondensing an oligomer obtained by an esterification reaction or a transesterification reaction between a diol component and a dicarboxylic acid component, usually, a titanium compound is used as a catalyst, and preferably, a Group 2A metal compound of the periodic table is further used. These catalyst components may be used in the esterification reaction or the transesterification reaction and the polycondensation reaction may be carried out as they are, or they may not be used in the esterification reaction, or only a titanium catalyst may be used and the remaining catalyst components may be added at the polycondensation stage. Further, in the esterification reaction or the transesterification reaction, a part of the finally used catalyst amount may be used and appropriately added as the polycondensation reaction proceeds. In any case, in the present invention, titanium and preferably a Group 2A metal of the periodic table are necessarily contained in the finally obtained PBT, and the amount thereof will be described later.

[0062] Specific examples of the titanium compound include inorganic titanium compounds such as titanium oxide and titanium tetrachloride, titanium alcoholates such as tetramethyl titanate, tetraisopropyl titanate, and tetrabutyl titanate, and titanium phenolates such as tetraphenyl titanate. These may be used alone or in combination of two or more. Among these, tetraalkyl titanate is preferable, and among them, tetrabutyl titanate is preferable.

[0063] The content of titanium in the PBT of the present invention is preferably 5 to 120 ppm in terms of the mass ratio of titanium atoms to PBT. This amount is more preferably 42 ppm or more, further preferably 45 ppm or more, and most preferably 50 ppm or more. Also, this amount is preferably 110 ppm or less, and more preferably 100 ppm or less. When the content of titanium is too large, the color tone, hydrolysis resistance, etc. deteriorate, and when it is too small, the polymerizability deteriorates.

[0064] Specific examples of the Group 2A metal compounds in the present invention include various compounds of beryllium, magnesium, calcium, strontium, and barium. However, from the viewpoints of handling ease, availability, and catalytic effect, magnesium compounds and / or calcium compounds are preferred, and particularly, magnesium compounds with excellent catalytic effects are preferred. Specific examples of magnesium compounds include magnesium acetate, magnesium hydroxide, magnesium carbonate, magnesium oxide, magnesium alkoxide, magnesium hydrogen phosphate, etc. Specific examples of calcium compounds include calcium acetate, calcium hydroxide, calcium carbonate, calcium oxide, calcium alkoxide, calcium hydrogen phosphate, etc. These Group 2A metal compounds in the periodic table may be used alone or in combination of two or more. Among these, magnesium acetate is most preferred.

[0065] The content of the Group 2A metal in the PBT of the present invention is not particularly limited, but it 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, and even more preferably 10 ppm or more. Also, 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. 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 polymerizability deteriorates. When using the acetate salt of the Group 2A metal in the periodic table, since the acetic acid source enters the reaction system, the amount of the Group 2A metal in PBT is preferably 15 ppm or less.

[0066] 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 even more preferably 0.3 to 1.5.

[0067] The metal content such as titanium atoms in PBT can be measured using methods such as atomic emission, atomic absorption, Inductively Coupled Plasma (ICP), etc. after recovering the metal in the polymer by methods such as wet ashing.

[0068] In the production of the PBT of the present invention, in addition to the above-mentioned titanium compounds and Group 2A metal compounds of the periodic table, 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, and phosphorus compounds such as their esters and metal salts, and reaction aids such as sodium hydroxide and sodium benzoate may be used. However, if nitrogen-containing organic bases or organic phosphorus compounds are present in any process of the esterification reaction or transesterification reaction and the subsequent polycondensation reaction, they will cause deterioration of the respective reactivities in the esterification reaction or transesterification reaction and the polycondensation reaction. Therefore, it is preferable not to add nitrogen-containing organic bases or organic phosphorus compounds in the esterification reaction or transesterification reaction and the polycondensation reaction.

[0069] The PBT obtained by the polycondensation reaction is usually withdrawn in a strand or sheet form from the outlet provided at the bottom of the polycondensation reaction tank, and then cut into granular bodies such as pellets or chips (for example, about 3 to 10 mm in length) while being water-cooled or after water-cooling. As the polycondensation method, either batch polymerization or continuous polymerization may be used, and it can be applied to either the transesterification reaction or the direct polymerization reaction. However, from the viewpoint of end group introduction, batch polymerization is preferably used.

[0070] (Polymerization temperature) In the production of the PBT of the present invention, the polymerization temperature (also referred to as the "polycondensation temperature") is a very important production condition. That is, when the polymerization temperature is as high as 250°C as in the aforementioned Patent Document 1, the resulting PBT has an increased number of terminal vinyl groups generated by the decomposition of the main chain and the terminal hydroxyl groups, and a decreased number of terminal hydroxyl groups. As a result, while an effect of lowering the dielectric loss tangent can be obtained, the coloring of PBT due to decomposition becomes remarkable, which is not preferable in terms of PBT quality. On the other hand, when the polymerization temperature is as low as 245°C as in the aforementioned Patent Document 4, the number of terminal vinyl groups generated by the decomposition of the main chain and the terminal hydroxyl groups is extremely small. Therefore, the effect on the low dielectric loss tangent derived from the terminal vinyl groups is small, and a good dielectric loss tangent cannot be obtained. From the above, in the production of PBT of the present invention, the polymerization temperature is preferably controlled to exceed 245°C and be less than 250°C, particularly 246 - 249°C, and especially 247 - 248°C.

[0071] [Compounding] The PBT of the present invention can be made into a compound product by adding various additives or compounding materials as necessary after the PBT production stage or after PBT is produced. Such additives are not particularly limited. For example, in addition to stabilizers such as antioxidants and heat stabilizers, lubricants, mold release agents, catalyst deactivators, crystal nucleating agents, crystallization accelerators, etc. can be mentioned. These additives can be added during or after the polymerization. Further, in order to impart desired performance to PBT, stabilizers such as ultraviolet absorbers and weather stabilizers, colorants such as dyes and pigments, antistatic agents, foaming agents, plasticizers, impact resistance improvers, etc. can be compounded. Also, as described above, a terminal capping agent can be added.

[0072] For example, as antioxidants, phenolic 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 can be added.

[0073] Also, as a release agent, paraffin wax, microcrystalline wax, polyethylene wax, long-chain fatty acids and their esters typified by montanic acid and montanic acid ester, silicone oil, etc. may be added.

[0074] In addition, a reinforcing filler can be compounded with the PBT of the present invention. The reinforcing filler is not particularly limited, and examples thereof include inorganic fibers such as glass fiber, carbon fiber, silica·alumina fiber, zirconia fiber, boron fiber, boron nitride fiber, silicon nitride potassium titanate fiber, and metal fiber, and organic fibers such as aromatic polyamide fiber and fluororesin fiber. These reinforcing fillers can also be used in combination of two or more. Among the above-mentioned reinforcing fillers, inorganic fillers, particularly glass fiber, are preferably used. When the reinforcing filler is an inorganic fiber or an organic fiber, its 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. Also, the average fiber length is not particularly limited, but is usually 0.1 to 20 mm, preferably 1 to 10 mm.

[0075] The reinforcing filler is preferably surface-treated with a sizing agent or a surface treatment agent in order to improve the interfacial adhesion with PBT. Examples of the sizing agent or the surface treatment agent 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 a surface treatment agent, or a sizing agent or a surface treatment agent can be added for surface treatment during the preparation of the PBT composition. The addition amount of the reinforcing filler is usually 150 parts by mass or less, preferably 5 to 100 parts by mass, based on 100 parts by mass of PBT.

[0076] Other fillers can be compounded with the PBT of the present invention together with the reinforcing filler. Examples of the other fillers to be compounded include plate-like inorganic fillers, ceramic beads, asbestos, wollastonite, talc, clay, mica, zeolite, kaolin, potassium titanate, barium sulfate, titanium oxide, silicon oxide, aluminum oxide, magnesium hydroxide, and the like. These can also be used in combination of two or more. By compounding a plate-like inorganic filler, the anisotropy and warpage of the obtained molded product can be reduced. Examples of the plate-like inorganic filler include glass flakes, mica, and metal foils. Among these, glass flakes are preferably used.

[0077] In addition, a flame retardant can be compounded into the PBT of the present invention to impart flame retardancy. The flame retardant is not particularly limited, and examples thereof include organic halogen compounds, antimony compounds, phosphorus compounds, other organic flame retardants, and inorganic flame retardants. Examples of the organic halogen compound include brominated polycarbonate, brominated epoxy resin, brominated phenoxy resin, brominated polyphenylene ether resin, brominated polystyrene resin, brominated bisphenol A, and polypentabromobenzyl acrylate. Examples of the antimony compound include antimony trioxide, antimony pentoxide, and sodium antimonate. Examples of the phosphorus compound include phosphate ester, 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 can also be used in combination of two or more kinds.

[0078] Thermoplastic resins such as polyethylene, polypropylene, polystyrene, polyacrylonitrile, polymethacrylate, ABS resin, polycarbonate, polyamide, polyphenylene sulfide, polyethylene terephthalate, liquid crystal polyester, polyacetal, and polyphenylene oxide, and thermosetting resins such as phenol resin, melamine resin, silicone resin, and epoxy resin can be compounded into the PBT of the present invention as necessary. These thermoplastic resins and thermosetting resins can also be used in combination of two or more kinds.

[0079] The compounding method of the above-mentioned various additives and additional components such as resins is not particularly limited, but a method of melt-kneading into PBT pellets using a single-screw or twin-screw extruder having a facility capable of devolatilization from a vent port is preferable. Each component, including the additional components, can be supplied to the kneader all at once or sequentially. Also, two or more kinds of components selected from each component, including the additional components, can be premixed.

[0080] When using the PBT of the present invention as at least a part of the raw materials and performing melt kneading by an extruder to obtain the compound product of the present invention as described above, it is preferable that the kneading resin temperature in the extruder is 320 ° C or lower. If this kneading resin temperature is 320 ° 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 still 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 preferably 250 ° C or higher.

[0081] [Molded article] The molded article of the present invention is formed by molding the PBT of the present invention or the PBT composition of the present invention containing various additives, inorganic fillers, etc. of the present invention. The molding method is not particularly limited, and molding methods generally used for thermoplastic resins, that is, injection molding, hollow molding, extrusion molding, press molding, etc. can be applied.

[0082] [Injection molding] Among the above molding methods, when used for automotive parts and electrical and electronic parts, it is preferable to use an injection molding machine. The melt resin temperature during this injection molding is preferably 280 ° C or lower. If this melt resin temperature is 280 ° C or lower, it is preferable in terms of suppressing thermal decomposition. From this viewpoint, the melt resin temperature during injection molding is more preferably 275 ° C or lower, and still more preferably 270 ° C or lower. On the other hand, from the viewpoint of ensuring uniform meltability, the melt resin temperature during injection molding is preferably 240 ° C or higher, particularly preferably 250 ° C or higher.

[0083] [Applications] Due to its excellent mechanical properties and heat resistance, the molded article of the present invention can be suitably used as a molded article selected from mechanical mechanism parts, electrical parts, electronic parts, and automotive parts. Among these, the molded article of the present invention is particularly useful for high-frequency transmission parts because of its excellent dielectric properties in the high-frequency band. It is also useful as a metal composite molded product in which a metal part composed of a connector, a cover, a terminal assembly, etc. integrally formed with a metal and a molded product made of the PBT of the present invention or the PBT composition of the present invention are integrated.

[0084] Specific examples of mechanical mechanism parts, electrical parts, electronic parts, and automotive parts include breakers, electromagnetic switches, focus cases, flyback transformers, molded products for fixing devices of copiers and printers, housings of general household appliances and OA equipment, varicon case parts, various terminal boards, transformers, printed wiring boards, housings, terminal blocks, coil bobbins, connectors, relays, disk drive chassis, transformers, switch parts, outlet parts, motor parts, sockets, plugs, capacitors, various cases, resistors, electrical and electronic parts incorporating metal terminals and conducting wires, computer-related parts, sound parts such as acoustic parts, lighting parts, telecommunications equipment-related parts, telephone equipment-related parts, air conditioner parts, home appliance parts such as VTRs and TVs, parts for copiers, parts for facsimiles, parts for optical equipment, automotive ignition device parts, automotive connectors, and various automotive electrical parts.

[0085] Furthermore, specific examples of high-frequency transmission parts include antenna substrates, connectors, housings, antenna covers, sensor covers, communication equipment using Bluetooth, wireless equipment used for drones, etc., which are electrical and electronic parts used in in-vehicle communication equipment such as 5G mobile communication terminals, communication base stations, quasi-millimeter wave sensors, millimeter wave sensors, and ETC. Among these, particularly as the metal composite molded product, there are connectors, covers, terminal assemblies, etc. used for them.

[0086] [Use of recycled raw materials] When molding the PBT of the present invention or the PBT composition of the present invention, from the viewpoints of waste reduction, cost reduction, and the improvement effect of the present invention, recycled raw materials may be used as at least a part of the molding material. Even in this case, if the use ratio of the recycled raw materials is below a predetermined value, the decrease in physical properties is within an acceptable range and is preferable.

[0087] Here, as the recycled raw material, there may be mentioned parts other than the molded products generated when molding using the PBT pellets of the present invention, parts having no commercial value generated during production typified by film ends or sheet ends, and the like. At this time, runners, spools, film ends, sheet ends, etc. may be recycled in their original shapes, or when it causes inconvenience in production, such as adversely affecting the bite-in property to the screw of the raw material feeder or molding machine, processing such as granulation, cutting, pulverization, etc. may be performed.

[0088] When the ratio of the recycled raw material in the raw material or material is A for the mass of all the raw materials or all the materials including the recycled raw material and C for the mass of the recycled raw material, it is preferable to satisfy the following formula (1). Among them, it is recommended to satisfy the following formula (2), particularly the following formula (3). 0.01 ≦ C / A ≦ 0.5 ····· (1) 0.05 ≦ C / A ≦ 0.4 ····· (2) 0.10 ≦ C / A ≦ 0.3 ····· (3) When the ratio of the recycled raw material is high, it causes deterioration of the color tone, increase of foreign matters, and increase of the terminal carboxyl group concentration. When the ratio of the recycled raw material is low, sufficient effects cannot be obtained in waste reduction, cost reduction, etc.

Examples

[0089] Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples in any way as long as it does not exceed the gist thereof.

[0090] [Evaluation and Measurement Methods] The measurement methods of the physical properties and evaluation items adopted in the following examples are as follows.

[0091] (1) Intrinsic viscosity (IV) It was determined in the following manner using an Ubbelohde viscometer. That is, using a mixed solvent of phenol / tetrachloroethane (mass ratio 1 / 1), at 30 °C, the dropping seconds of a PBT solution with a concentration of 1.0 g / dL and the solvent only were measured, and it was determined from the following formula. IV = ((1 + 4K H η sp ) 0.5 - 1) / (2K H ·C) (where η sp = η0 - 1, η is the dropping seconds of the PBT solution, η0 is the dropping seconds of the solvent, C is the PBT solution concentration (g / dL), and K H is the Huggins constant, and 0.33 was adopted.)

[0092] (2) Titanium and Group 2A metal concentrations in the periodic table PBT was wet-decomposed with high-purity sulfuric acid and nitric acid for the electronics industry and measured using a high-resolution ICP (Inductively Coupled Plasma)-MS (Mass Spectrometer) (manufactured by Thermo Quest).

[0093] (3) High-frequency dielectric properties (dielectric loss tangent) Thermal press forming was carried out at 250 °C to obtain a 100 mm × 100 mm square PBT test piece with a test piece thickness of 200 μm. This test piece was dried to a moisture content of 100 ppm or less to obtain a dried test piece. The moisture content of the dried test piece was measured using a Karl Fischer moisture meter KF200 (manufactured by Nitto Seiko Analytic Co., Ltd.). Using this dried test piece, the dielectric loss tangent was measured at 23 °C as follows. The dielectric loss tangents at frequencies of 1.1 GHz, 2.5 GHz, 5 GHz, and 10 GHz were obtained by the cylindrical cavity resonator perturbation method using a network analyzer N5290A manufactured by KEYSIGHT TECHNOLOGIES and a split post resonator manufactured by KEYSIGHT TECHNOLOGIES. Also, the dielectric loss tangents at frequencies of 20 GHz, 28 GHz, 40 GHz, 60 GHz, and 80 GHz were obtained by the cylindrical cavity resonator perturbation method using a network analyzer N5290A manufactured by KEYSIGHT TECHNOLOGIES and a split cylinder resonator manufactured by EM Lab.

[0094] (4) Monofunctional component concentration After dissolving 0.5 g of PBT pellets in 5 mL of hexafluoroisopropanol, 20 mL of methanol was added to precipitate the polymer. The precipitated polymer was filtered off with a filter, and the filtrate was analyzed by GC-MS (Agilent's "7890GC" / Agilent's "5977MSD"). Note that, if necessary, the filtrate may be concentrated and analyzed by GC-MS. GC / MS measurement was performed to confirm the amount of monofunctional components.

[0095] (5) Terminal ester group concentration, terminal vinyl group concentration, terminal hydroxyl group concentration PBT was dissolved in a mixed solvent of deuterated chloroform / deuterated hexafluoroisopropanol / deuterated pyridine (21 / 9 / 1 volume ratio) containing a small amount of tetramethylsilane, and using an AVANCE NEO spectrometer (manufactured by Bruker) 1 the 1H NMR spectrum was measured. The reference for the chemical shift was set such that the signal of tetramethylsilane was 0.00 ppm.

[0096] (6) Terminal carboxyl group concentration 0.5 g of PBT or oligomer was dissolved in 25 mL of benzyl alcohol, and titration was performed using a 0.01 mol / L benzyl alcohol solution of sodium hydroxide to determine it.

[0097] Using a color difference meter "Z-300A type" manufactured by Nippon Denshoku Industries Co., Ltd., evaluation was performed in the L, a, b color system. The lower the b value, the less yellowish color is preferred. However, if it is excessively low, although the yellow tint is less, the blue tint increases and the color tone is not preferred. The b value is preferably in the range of -2.0 to 0.0.

[0098] [Production Example of Biomass-Derived 1,4-Butanediol] [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 solution. The obtained mixed solution was subjected to vacuum distillation to obtain a first fraction, a main fraction, and a residue in the order of distillation. When a part of the obtained main fraction was taken out and analyzed by gas chromatography, the 1,4-butanediol content was 99% by mass or more.

[0099] [Production Example of Chemical Recycling 1,4-Butanediol] <Production Example 2: 1,4-Butanediol by Depolymerization of PBT> Following Example 3 of JP-A-2004-323378, chemical recycling BDO was produced. 1030 parts by mass of polybutylene terephthalate, 3200 parts by mass of methanol, and 13 parts by mass of sodium carbonate were supplied to an autoclave equipped with a stirring blade. The autoclave was immersed in an oil bath at 200 °C and reacted with stirring at a pressure of 1.3 MPa for 8 hours. The autoclave was taken out of the oil bath and cooled to 10 °C or lower with ice water to obtain a slurry liquid. The obtained slurry liquid was subjected to solid-liquid separation with filter paper to obtain a filtrate. The obtained filtrate was put into a distillation apparatus equipped with a thermometer, a vacuum control device, a stirring blade, a condenser, and a fraction receiver. After recovering methanol and tetrahydrofuran as the initial fraction, vacuum distillation was carried out to obtain a first fraction, a main fraction, and a residue in the order of distillation. When a part of the obtained main fraction was taken out and analyzed by gas chromatography, the 1,4-butanediol content was 99% by mass or more.

[0100] [Production Example of Chemical Recycling Dimethyl Terephthalate] <Production Example 3: Chemical Recycling Dimethyl Terephthalate 1> Referring to the method described in JP-A-2001-151934, chemical recycling dimethyl terephthalate 1 was obtained as follows. Into a flask equipped with a fraction collector, a stirrer, and a thermometer, 100 parts by mass of waste fibers made of polyethylene terephthalate, 100 parts by mass of ethylene glycol, and 1.5 parts by mass of sodium carbonate were placed. This flask was immersed in an oil bath at 210 °C and reacted for 10 hours while extracting light-boiling components to obtain a depolymerization reaction solution 1. The obtained depolymerization reaction solution 1 was hot-filtered with a glass filter to obtain filtrate 1. To the obtained filtrate 1, 200 parts by mass of methanol and 0.5 parts by mass of sodium carbonate were added, and the mixture was reacted at 65 °C for 1 hour to obtain reaction solution 2. The obtained reaction solution 2 was placed in a vacuum distillation apparatus equipped with a fraction collector, a Liebig condenser, a stirrer, a thermometer, and a pressure controller. The distillation apparatus was immersed in an oil bath, and while observing the distillate, the temperature and pressure of the oil bath were controlled to obtain a fore-fraction, a main fraction, and a bottom residue in the order of distillation. The obtained main fraction and xylene were placed in an eggplant flask, heated to form a homogeneous solution, and then cooled to room temperature for crystallization to obtain a slurry. The obtained slurry was filtered with a glass filter to obtain a cake. The obtained cake was placed in an eggplant flask and attached to an evaporator equipped with an oil bath, and xylene was distilled off from the cake under reduced pressure to obtain a white solid. When a part of the obtained white solid was taken out and analyzed by gas chromatography, the content of dimethyl terephthalate was 99% by mass or more.

[0101] <Production Example 4: Chemical Recycling Dimethyl Terephthalate 2> Referring to the method described in JP-A-2004-323378, chemical recycling dimethyl terephthalate 2 was obtained as follows. Into an autoclave equipped with a stirrer and a thermometer, 100 parts by mass of waste fibers made of polyethylene terephthalate, 300 parts by mass of methanol, and 1.5 parts by mass of sodium carbonate were placed. This autoclave was immersed in an oil bath at 150 °C and reacted at 1.3 MPa for 10 hours. Then, a distilling tube was attached to the autoclave, the pressure was slowly reduced to normal pressure, and light-boiling components were distilled off to obtain a depolymerization reaction solution 1. After the temperature of the obtained depolymerization reaction solution 1 was lowered to room temperature, xylene was added, and the mixture was immersed in an oil bath at 120 °C to obtain Slurry 1. The obtained Slurry 1 was filtered through a glass filter, cooled to room temperature for crystallization, and Slurry 2 was obtained. 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 collector, a stirrer, and a thermometer, and then immersed in an oil bath. While observing the distillate, the temperature and pressure of the oil bath were controlled to obtain a first fraction, a main fraction, and a residue in the order of distillation. When a part of the obtained main fraction was taken out and analyzed by gas chromatography, the content of dimethyl terephthalate was 99% by mass or more.

[0102] <Production Example 5: Chemical Recycling Dimethyl Terephthalate 3> With reference to the method described in JP-A-2001-151934, chemical recycling dimethyl terephthalate 3 was obtained as follows. 100 parts by mass of polybutylene terephthalate containing a glass filler and 200 parts by mass of methanol were placed in an autoclave equipped with a stirrer and a thermometer. This autoclave was immersed in an oil bath at 170 °C and reacted at 5.5 MPa for 5 hours. Then, the autoclave was taken out of the oil bath and cooled to room temperature to obtain a depolymerization reaction solution 1. The obtained depolymerization reaction solution 1 was filtered through a glass filter to obtain a solid content. Tetrahydrofuran was added to the obtained solid content to dissolve the white solid contained in the solid content, and the glass filler was removed as a filtrate by filtration to obtain Solution 1. The obtained Solution 1 was placed in a flask equipped with a fraction collector, a stirrer, and a thermometer, and then immersed in an oil bath. While observing the distillate, the temperature and pressure of the oil bath were controlled to obtain a light-boiling component containing tetrahydrofuran, a first fraction, a main fraction, and a residue in the order of distillation. When a part of the obtained main fraction was taken out and analyzed by gas chromatography, the content of dimethyl terephthalate was 99% by mass or more.

[0103] [Production Example of Chemically Recycled Terephthalic Acid] <Production Example 6: Chemically Recycled Terephthalic Acid 1> In the same manner as in Production Example 3, a white solid of dimethyl terephthalate having a dimethyl terephthalate content of 99% by mass or more (chemically recycled dimethyl terephthalate 1) was obtained. The obtained white solid of dimethyl terephthalate 1 was dissolved in methylene chloride, and a methanol solution of potassium hydroxide was added thereto for hydrolysis to obtain Reaction Solution 1. To the obtained Reaction Solution 1, 60% by mass of sulfuric acid was added for neutralization to obtain Slurry 2. The obtained Slurry 2 was filtered with a centrifuge to obtain Cake 2. The obtained Cake 2 was supplied to pure water and mixed to obtain Slurry 3. The obtained Slurry 3 was filtered with a centrifuge to obtain Cake 3. The obtained Cake 3 was again supplied to pure water and mixed to obtain Slurry 4. The obtained Slurry 4 was filtered with a centrifuge to obtain Cake 4. The obtained Cake 4 was placed in an eggplant flask, attached to an evaporator equipped with an oil bath, and volatile components were distilled off from Cake 4 under reduced pressure to obtain white solid terephthalic acid 1. When a part of the obtained white solid was analyzed by liquid chromatography, the terephthalic acid content was 99% by mass or more.

[0104] <Production Example 7: Chemically Recycled Terephthalic Acid 2> In the same manner as in Production Example 4, a main fraction having a dimethyl terephthalate content of 99% by mass or more was obtained. Using this main fraction of dimethyl terephthalate (chemically recycled dimethyl terephthalate 2) instead of the white solid of dimethyl terephthalate, hydrolysis and purification were carried out in the same manner as in Production Example 6 to obtain white solid terephthalic acid 2 having a terephthalic acid content of 99% by mass or more.

[0105] <Production Example 8: Chemically Recycled Terephthalic Acid 3> In the same manner as in Production Example 5, a main fraction having a dimethyl terephthalate content of 99% by mass or more was obtained. Using this main fraction of dimethyl terephthalate (chemically recycled dimethyl terephthalate 3) instead of the white solid of dimethyl terephthalate, hydrolysis and purification were carried out in the same manner as in Production Example 6 to obtain white solid terephthalic acid 3 having a terephthalic acid content of 99% by mass or more.

[0106] [Raw Materials Used, etc.] The raw materials used other than those manufactured in the above production example are as follows. Petrochemical-derived terephthalic acid: High-purity terephthalic acid manufactured by PT Mitsubishi Chemical Indonesia Petrochemical-derived DMT: Manufactured by SK Petrochemical Petrochemical-derived BDO: BDO manufactured by Mitsubishi Chemical Corporation by the butadiene method

[0107] [Example 1] Using petrochemical-derived BDO as the BDO in the raw materials BDO of PBT, the BDO solution of tetrabutyl titanate, and the BDO solution of magnesium acetate tetrahydrate, PBT was produced by the following method. Into a stainless steel reaction tank equipped with a turbine-type stirring blade, 397.2 parts by mass of petrochemical-derived DMT, 213.8 parts by mass of BDO (BDO / DMT molar ratio = 1.16), 16.8 parts by mass of 2-dodecyl-1-hexadecanol (2 mol% based on dimethyl terephthalate), 1.75 parts by mass of a 6% by mass BDO solution of tetrabutyl titanate (tetrabutyl titanate is 33 ppm by mass as titanium element based on the theoretical polymer yield) were added, and a transesterification reaction was carried out at 150 to 215 °C for 2 hours. Then, 1.9 parts by mass of a 10% by mass BDO solution of magnesium acetate tetrahydrate (magnesium acetate is 48 ppm by mass as magnesium element based on the theoretical polymer yield) was added, and further, 3.25 parts by mass of a 6% by mass BDO solution of tetrabutyl titanate (tetrabutyl titanate is 61 ppm by mass as titanium element based on the theoretical polymer yield) was added. Subsequently, the oligomer obtained above was transferred to a stainless steel reaction tank having a vent pipe and a double helical stirring blade, and then a polycondensation reaction was carried out. The polycondensation reaction was gradually depressurized from normal pressure to 0.133 kPa over 85 minutes, and at the same time, the temperature was raised to a predetermined polymerization temperature of 247 °C. Thereafter, it was continued at the predetermined polymerization temperature and 0.133 kPa, and the predetermined stirring torque was reached in 2 hours and 40 minutes, and the reaction was terminated. The obtained polymer was continuously extruded in a strand shape from a die head and cut with a rotary cutter to obtain PBT pellets (major axis: about 3 mm, minor axis: about 2 mm, length: about 4 mm). The inherent viscosity (IV) of the obtained PBT was 0.90 dL / g.

[0108] [Examples 2 to 4, Examples 9 to 12, Examples 17 to 20] In Example 1, except that the raw material BDO of PBT, the BDO for various BDO solutions, and the raw material DMT were changed to those described in Tables 1 to 3, the same procedure as in Example 1 was carried out.

[0109] [Example 5] Using petrochemical-derived BDO as the raw material BDO of PBT, the BDO of the BDO solution of tetrabutyl titanate, and the BDO of the BDO solution of magnesium acetate tetrahydrate, PBT was produced by the following method. A slurry obtained by mixing 754.3 parts by mass of terephthalic acid (TPA) and 736.6 parts by mass of BDO (BDO / TPA molar ratio = 1.80) as described in Table 1 was added to the esterification reaction tank so as to be 1000 parts by mass as the polymer (PBT). Next, 458.2 parts by mass of the same BDO was added (total BDO / TPA molar ratio = 3.20). To the esterification reaction tank, 37.3 parts by mass of 2-dodecyl-1-hexadecanol (2 mol% based on terephthalic acid) and a BDO solution of tetrabutyl titanate in an amount such that titanium was 40 ppm with respect to PBT were added. The temperature of the liquid in the tank was raised from 150 °C to 220 °C over 90 minutes and held at 220 °C for 60 minutes. During this time, while distilling off the generated water, an esterification reaction was carried out for a total of 180 minutes. The esterification reaction was carried out under nitrogen at normal pressure.

[0110] Fifteen minutes before the end of the esterification reaction, magnesium acetate tetrahydrate was dissolved in BDO and added so as to be 10 ppm by mass in terms of magnesium element with respect to the PBT to be produced, and then it was transferred to a polycondensation reaction tank equipped with a stirrer, a nitrogen inlet, a heating device, a thermometer, a distillation tube, and a vacuum exhaust port, and a vacuum was applied to carry out a polycondensation reaction. The polycondensation reaction was gradually depressurized from normal pressure to 0.4 KPa over 85 minutes in the tank, and continued at 0.4 KPa or less. The reaction temperature was maintained at 220 °C for 15 minutes from the start of depressurization, and then heated to 240 °C over 45 minutes and maintained at this temperature. The reaction was terminated when a predetermined stirring torque was reached. The time required for the polycondensation reaction was 190 minutes. Next, the inside of the polycondensation reaction tank was repressurized with nitrogen from the depressurized state, and then pressurized for polymer extraction. The polymer was extruded in a strand shape from the die with the heat medium temperature of the die at the time of extraction being 235 °C, and then the strand was cooled in a cooling water tank, and then cut with a strand cutter to be pelletized.

[0111] [Examples 6 - 8, Examples 13 - 16, Examples 21 - 24] In Example 5, it was carried out in the same manner as in Example 5, except that the raw material BDO of PBT and the BDO for various BDO solutions and the raw material TPA were changed to those described in Tables 1 - 3.

[0112] [Comparative Example 1] In Example 1, it was carried out in the same manner as in Example 1, except that 2 - dodecyl - 1 - hexadecanol was not added.

[0113] [Comparative Example 2] (Conforming to the polymerization temperature of Example 1 of International Publication No. 2021 / 020208.) Using petrochemical - derived BDO as the raw material BDO of PBT and the BDO for various BDO solutions, PBT was produced by the following method. To a stainless - steel reaction tank equipped with a turbine - type stirring blade, 340.0 parts by mass of petrochemical - derived TPA, 313.8 parts by mass of BDO (BDO / TPA molar ratio = 1.70), 16.8 parts by mass of 2 - dodecyl - 1 - hexadecanol (2 mol% with respect to terephthalic acid), and 1.87 parts by mass of a BDO solution of 6% tetrabutyl titanate (tetrabutyl titanate is 35 ppm by mass as titanium element with respect to the theoretical polymer yield) were added, and the esterification reaction was started under reduced pressure at a temperature of 160 °C and a pressure of 90 kPa. Thereafter, the temperature was gradually increased, and finally, an esterification reaction was carried out under the condition of a temperature of 225°C. The completion of the esterification reaction was confirmed by the state of the distillate, etc., and the reaction time of the esterification reaction was set to 3 hours. Subsequently, the oligomer obtained above was transferred to a reaction tank equipped with a vent pipe and a double helical stirring blade, and then 35 ppm of titanium element was added as a polycondensation reaction catalyst, and a polycondensation reaction was carried out under the conditions of a temperature of 245°C and a pressure of 100 Pa. The completion of the polycondensation reaction was confirmed by the viscosity of the reaction product, etc., and the polycondensation reaction time for obtaining PBT was set to 2 hours and 50 minutes, and PBT was obtained.

[0114] [Comparative Example 3] (Conforming to the polymerization temperature of Example 1 of JP-A-10-310638.) Using petrochemical-derived BDO as the BDO of the raw materials BDO of PBT, the BDO solution of tetrabutyl titanate, and the BDO solution of magnesium acetate tetrahydrate, PBT was produced by the following method. To a stainless steel reaction tank equipped with a turbine-type stirring blade, 397.2 parts by mass of petrochemical-derived DMT, 258.1 parts by mass of BDO (BDO / DMT molar ratio = 1.40), 16.8 parts by mass of 2-dodecyl-1-hexadecanol (2 mol% based on dimethyl terephthalate), and 3.74 parts by mass of a 6% by mass BDO solution of tetrabutyl titanate (tetrabutyl titanate is 70 ppm by mass of titanium element based on the theoretical polymer yield) were added, and a transesterification and esterification reaction was carried out while raising the temperature from 140 to 200°C over 90 minutes. At this time, methanol and water reached about 90% of the theoretical amount. Subsequently, the oligomer obtained above was transferred to a reaction tank equipped with a vent pipe and a double helical stirring blade, and then a polycondensation reaction was carried out. The pressure was gradually reduced while raising the temperature from 200°C to 250°C and reached 0.5 torr in about 40 minutes. A polymerization reaction was carried out at 250°C and 0.5 torr for 2 hours, the polymer was taken out and pelletized to obtain PBT.

[0115] The intrinsic viscosity (IV), b value, terminal carboxyl group concentration, terminal hydroxyl group concentration, terminal ester group concentration, terminal vinyl group concentration, and monofunctional component concentration of the PBT obtained in Examples 1 to 24 and Comparative Examples 1 to 3 are shown in Tables 1 to 3 together with the production conditions of the PBT. The measurement results of the dielectric loss tangent of the obtained PBT are shown in Tables 4 to 6.

[0116] In the following Tables 1 to 3, Dimethyl Terephthalate 1, Dimethyl Terephthalate 2, and Dimethyl Terephthalate 3 for chemical recycling are described as "CR-DMT1", "CR-DMT2", and "CR-DMT3", respectively. Also, Terephthalic Acid 1, Terephthalic Acid 2, and Terephthalic Acid 3 for chemical recycling are described as "CR-TPA1", "CR-TPA2", and "CR-TPA3", respectively.

[0117] [Table 1]

[0118] [Table 2]

[0119] [Table 3]

[0120] [Table 4]

[0121] [Table 5]

[0122] [Table 6]

[0123] As shown in Tables 1 to 6, the PBTs of Examples 1 to 24 that meet the requirements of the present invention have a low dielectric loss tangent even in the high-frequency band, a small ratio of the dielectric loss tangents at a predetermined frequency, and are PBTs that are also favorable with respect to color tone. Such an effect of the present invention is achieved even when biomass-derived BDO or chemical recycle BDO is used as the raw material BDO of PBT, and also when biomass-derived terephthalic acid, dimethyl terephthalate, chemical recycle terephthalic acid or dimethyl terephthalate is used as the terephthalic acid component of the raw material of PBT. On the other hand, the PBTs of Comparative Examples 1 to 3 that do not meet the requirements of the present invention had a high dielectric loss tangent in the high-frequency band, a large ratio of the dielectric loss tangents at a predetermined frequency, and were PBTs that were not favorable with respect to color tone.

Claims

1. A polybutylene terephthalate having terminal ester groups, wherein the intrinsic viscosity (IV) of the polybutylene terephthalate is 0.7 to 1.3 dL / g, The dielectric tangent (DDF ６０ ), measured by the following method, at a frequency of 60 GHz is 0.003 to 0.0055, and the ratio (DDF ５ / DDF ６０ ) of the dielectric tangent (DDF ６０ ) at a frequency of 60 GHz to the dielectric tangent (DDF ５ ) at a frequency of 5 GHz is 0.9 to 1.20, and the terminal vinyl group concentration is 3 to 20 equivalents / ton. The polybutylene terephthalate is characterized by the above. <Method for Measuring Dielectric Loss Tangent> For a dry test piece with a water content of 100 ppm or less obtained by molding the polybutylene terephthalate, the dielectric loss tangent is measured at a predetermined frequency under the temperature condition of 23 °C by the cylindrical cavity resonator perturbation method.

2. A polybutylene terephthalate having terminal ester groups, wherein the intrinsic viscosity (IV) of the polybutylene terephthalate is 0.7 to 1.3 dL / g, The dielectric tangent (DDF ８０ ) measured by the following method is 0.003 to 0.006, and the ratio (DDF ５ ) of the dielectric tangent (DDF ８０ ) at a frequency of 80 GHz to the dielectric tangent (DDF ８０ / DDF ５ ) at a frequency of 5 GHz is 0.95 to 1.29, and the terminal vinyl group concentration is 3 to 20 equivalents / ton. The polybutylene terephthalate is characterized by the above. <Method for Measuring Dielectric Loss Tangent> For a dry test piece with a water content of 100 ppm or less obtained by molding the polybutylene terephthalate, the dielectric loss tangent is measured at a predetermined frequency under the temperature condition of 23 °C by the cylindrical cavity resonator perturbation method.

3. A polybutylene terephthalate having terminal ester groups, wherein the intrinsic viscosity (IV) of the polybutylene terephthalate is 0.7 to 1.3 dL / g, The dielectric dissipation factor (DDF ６０ ) measured by the following method is 0.003 to 0.0055 at a frequency of 60 GHz, and the dielectric dissipation factor (DDF １．１ ) is 0.003 to 0.005 at a frequency of 1.1 GHz, and the ratio (DDF ５ ) of the dielectric dissipation factor (DDF １．１ ) at a frequency of 1.1 GHz to the dielectric dissipation factor (DDF １．１ / DDF ５ ) is 0.9 to 1.2, and the terminal vinyl group concentration is 3 to 20 equivalents / ton. The polybutylene terephthalate is characterized by the above. <Method for Measuring Dielectric Loss Tangent> For a dry test piece with a water content of 100 ppm or less obtained by molding the polybutylene terephthalate, the dielectric loss tangent is measured at a predetermined frequency under the temperature condition of 23 °C by the cylindrical cavity resonator perturbation method.

4. A polybutylene terephthalate having terminal ester groups, wherein the intrinsic viscosity (IV) of the polybutylene terephthalate is 0.7 to 1.3 dL / g, The dielectric tangent (DDF ６０ ) measured by the following method at a frequency of 60 GHz is 0.003 to 0.0055, and the dielectric tangent (DDF ２．５ ) at a frequency of 2.5 GHz is 0.003 to 0.

005. The ratio (DDF ５ ) of the dielectric tangent (DDF ２．５ ) at a frequency of 2.5 GHz to the dielectric tangent (DDF ２．５ / DDF ５ ) is 0.9 to 1.2, and the terminal vinyl group concentration is 3 to 20 equivalents / ton. The polybutylene terephthalate is characterized by the above. <Method for Measuring Dielectric Loss Tangent> For a dry test piece with a water content of 100 ppm or less obtained by molding the polybutylene terephthalate, the dielectric loss tangent is measured at a predetermined frequency under the temperature condition of 23 °C by the cylindrical cavity resonator perturbation method.

5. A polybutylene terephthalate having terminal ester groups, wherein the intrinsic viscosity (IV) of the polybutylene terephthalate is 0.7 to 1.3 dL / g, The dielectric tangent (DDF ６０ ) at a frequency of 60 GHz measured by the following method is 0.003 to 0.0055, and the dielectric tangent (DDF １０ ) at a frequency of 10 GHz is 0.003 to 0.

005. The ratio (DDF ５ ) of the dielectric tangent (DDF １０ ) at a frequency of 10 GHz to the dielectric tangent (DDF １０ / DDF ５ ) at a frequency of 5 GHz is 0.9 to 1.2, and the terminal vinyl group concentration is 3 to 20 equivalents / ton. The polybutylene terephthalate is characterized by the above. <Method for Measuring Dielectric Loss Tangent> For a dried test piece with a water content of 100 ppm or less obtained by molding the polybutylene terephthalate, the dielectric loss tangent is measured at a predetermined frequency under a temperature condition of 23°C by the cylindrical cavity resonator perturbation method.

6. A polybutylene terephthalate having terminal ester groups, wherein the intrinsic viscosity (IV) of the polybutylene terephthalate is 0.7 to 1.3 dL / g, The dielectric tangent (DDF ６０ ), measured by the following method, at a frequency of 60 GHz is 0.003 to 0.0055, the dielectric tangent (DDF ２０ ), at a frequency of 20 GHz is 0.003 to 0.005, and the ratio (DDF ５ / DDF ２０ ) of the dielectric tangent (DDF ２０ ) at a frequency of 20 GHz to the dielectric tangent (DDF ５ ) at a frequency of 5 GHz is 0.9 to 1.2, and the terminal vinyl group concentration is 3 to 20 equivalents / ton. The polybutylene terephthalate is characterized by this. <Method for Measuring Dielectric Loss Tangent> For a dried test piece with a water content of 100 ppm or less obtained by molding the polybutylene terephthalate, the dielectric loss tangent is measured at a predetermined frequency under a temperature condition of 23°C by the cylindrical cavity resonator perturbation method.

7. A polybutylene terephthalate having terminal ester groups, wherein the intrinsic viscosity (IV) of the polybutylene terephthalate is 0.7 to 1.3 dL / g, The dielectric tangent (DDF ６０ ) measured by the following method at a frequency of 60 GHz is 0.003 to 0.0055, and the dielectric tangent (DDF ２８ ) at a frequency of 28 GHz is 0.003 to 0.

005. The ratio (DDF ５ ) of the dielectric tangent (DDF ２８ ) at a frequency of 28 GHz to the dielectric tangent (DDF ２８ / DDF ５ ) at a frequency of 5 GHz is 0.9 to 1.2, and the terminal vinyl group concentration is 3 to 20 equivalents / ton. The polybutylene terephthalate is characterized by this. <Method for Measuring Dielectric Loss Tangent> For a dried test piece with a water content of 100 ppm or less obtained by molding the polybutylene terephthalate, the dielectric loss tangent is measured at a predetermined frequency under a temperature condition of 23°C by the cylindrical cavity resonator perturbation method.

8. A polybutylene terephthalate having terminal ester groups, wherein the intrinsic viscosity (IV) of the polybutylene terephthalate is 0.7 to 1.3 dL / g, The dielectric loss tangent (DDF ６０ ) measured by the following method is 0.003 to 0.0055 at a frequency of 60 GHz, and the dielectric loss tangent (DDF ４０ ) is 0.003 to 0.005 at a frequency of 40 GHz, and the ratio (DDF ５ ) of the dielectric loss tangent (DDF ４０ ) at a frequency of 40 GHz to the dielectric loss tangent (DDF ４０ / DDF ５ ) is 0.9 to 1.2, and the terminal vinyl group concentration is 3 to 20 equivalents / ton. The polybutylene terephthalate is characterized by this. <Method for Measuring Dielectric Loss Tangent> For a dried test piece with a water content of 100 ppm or less obtained by molding the polybutylene terephthalate, the dielectric loss tangent is measured at a predetermined frequency under a temperature condition of 23°C by the cylindrical cavity resonator perturbation method.

9. The polybutylene terephthalate according to any one of claims 1 to 8, wherein the raw material 1,4-butanediol of the polybutylene terephthalate contains 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 biomass resources, and 1,4-butanediol produced by depolymerization of polybutylene terephthalate.

10. The polybutylene terephthalate according to any one of claims 1 to 8, wherein the raw material terephthalic acid component of the polybutylene terephthalate contains either terephthalic acid or dimethyl terephthalate produced by chemical recycling of polyester, or terephthalic acid or dimethyl terephthalate produced using biomass resources.

11. A polybutylene terephthalate composition obtained by blending an additive and / or an inorganic filler with the polybutylene terephthalate according to any one of claims 1 to 8.

12. A molded article obtained by melt-molding the polybutylene terephthalate according to any one of claims 1 to 8 or the polybutylene terephthalate composition containing the polybutylene terephthalate.

13. The molded article according to claim 12, which is used as a component for high-frequency transmission.

14. A metal composite molded article in which the molded article according to claim 12 and a metal component are integrated.

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