JP3996876B2 - Production method of polyester resin - Google Patents

Description

【００６５】
【表２】

【００６６】
［実施例２］
２ｂを通して供給する触媒の量を表に示す通りに変更した以外は、実施例１と同様に行った。フィルター差圧上昇までの時間が長く、異物の少ないポリブチレンテレフタレートが得られた。
［実施例３］
２ｄを通して供給する１，４−ブタンジオールの量を表に示す通りに変更した以外は、実施例１と同様に行った。フィルター差圧上昇までの時間が長く、異物の少ないポリブチレンテレフタレートが得られた。
【００６７】
［実施例４］
攪拌回転数を変え、Ｐ／ｑを表に示す通りに変更した以外は、実施例３と同様に行った。フィルター差圧上昇までの時間が長く、異物の少ないポリブチレンテレフタレートが得られた。
［実施例５］
原料の流量を変えエステル化反応槽での平均滞留時間を１．１ｈｒとし、攪拌回転数を表に示す通りに変更した以外は、実施例１と同様に行った。フィルター差圧上昇までの時間が長く、異物の少ないポリブチレンテレフタレートが得られた。
【００６８】
［実施例６］
反応温度を２４０℃にした以外は実施例１と同様に行った。フィルター差圧上昇までの時間が長く、異物の少ないポリブチレンテレフタレートが得られた。
［実施例７］
フィルターの絶対濾過精度を２０．０μｍにした以外は実施例１と同様に行った。
【００６９】
［実施例８］
フィルターユニットを図６に示した位置、即ちエステル化反応槽の後に設置した以外は実施例１と同様に行った。
［実施例９］
２ｂを通して供給する触媒の量を表に示す通りに変更した以外は、実施例１と同様に行った。フィルター差圧上昇までの時間が長く、異物の少ないポリブチレンテレフタレートが得られた。
【００７０】
［実施例１０］
２ｂを通して供給する触媒の量を表に示す通りに変更した以外は、実施例１と同様に行った。フィルター差圧上昇までの時間が長く、異物の少ないポリブチレンテレフタレートが得られた。
［比較例１］
フィルターを使用しなかった以外は、実施例１と同様に行った。フィルム中の異物量が多く、モノフィラメント成型中の糸切れが頻発し、モノフィラメントの直線強度も低かった。
【００７１】
［比較例２］
２ｂを通して供給する触媒量を表に示す通りにした以外は実施例１と同様に行った。フィルターの差圧上昇までの時間が極端に短かった。
［比較例３］
攪拌回転数を変えＰ／ｑを表に示す通りにした以外は実施例１と同様に行った。フィルターの差圧上昇までの時間が極端に短かった。
【００７２】
［比較例４］
フィルターユニットを図７に示した位置、即ち第２縮重合反応槽の後に設置した以外は実施例１と同様に行った。フィルターに入る流体（ポリマー）の粘度が高く、フィルターの設計耐差圧以上になったため実験を中止した。
【００７３】
【発明の効果】
本発明によると、生産性を維持したままポリブチレンテレフタレート中の異物を抜本的に低減することができ、異物の極めて少ないフィルム、モノフィラメント等のポリブチレンテレフタレート樹脂成型物を提供することができるため産業上の効果が大きい。
【図面の簡単な説明】
【図１】本発明の好ましい一実施態様であるポリブチレンテレフタレートの製造装置の概略図である。
【図２】本発明の別の好ましい一実施態様であるポリブチレンテレフタレートの製造装置の概略図である。
【図３】本発明の別の好ましい一実施態様であるポリブチレンテレフタレートの製造装置の概略図である。
【図４】本発明の別の好ましい一実施態様であるポリブチレンテレフタレートの製造装置の概略図である。
【図５】実施例１で使用したポリブチレンテレフタレートの製造装置の概略図である。
【図６】実施例８で使用したポリブチレンテレフタレートの製造装置の概略図である。
【図７】比較例４で使用したポリブチレンテレフタレートの製造装置の概略図である。
【符号の説明】
１ スラリー調整槽
１ａ、１ｂ 原料供給口
２ エステル化反応槽
２ａ ベント用口
２ｂ 触媒供給口
２ｃ サンプリング口
２ｄ １，４−ブタンジオールの供給口
３ 第一重縮合反応槽
３ａ ベント用口
３ｂ サンプリング口
４ 第二重縮合反応槽
４ａ ベント用口
４ｂ サンプリング口
５ 第三重縮合反応槽
５ａ ベント用口
６、７、８ フィルターユニット
９ ポリマー抜き出しダイ
１０ 回転式カッター
Ｍ１、Ｍ２、Ｍ３、Ｍ４ 攪拌装置
Ｇ１、Ｇ２、Ｇ３、Ｇ４ ギアポンプ
Ｐ１ 原料供給配管
Ｐ２、Ｐ３、Ｐ４ 反応槽を繋ぐ配管
Ｐ５ ポリマー抜出配管[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing polybutylene terephthalate, and a film and monofilament using polybutylene terephthalate obtained by the production method. More specifically, the present invention relates to a method for producing polybutylene terephthalate in which the production of foreign matters during the esterification reaction is suppressed and the foreign matters in the product are greatly reduced, and a film and monofilament made of the polybutylene terephthalate.
[0002]
[Prior art]
Polybutylene terephthalate, a representative engineering plastic among thermoplastic polyester resins, is easy to process, mechanical properties, heat resistance, chemical resistance, fragrance retention, and other physical and chemical properties. It is widely used in injection molded products such as automobile parts, electrical / electronic parts, precision equipment parts, etc., but in recent years, it has been used in the fields of films, sheets, monofilaments, fibers, etc. But it has come to be widely used.
Polybutylene terephthalate is produced through an esterification reaction when terephthalic acid is used as a raw material, and a transesterification reaction when dialkyl terephthalate is used as a raw material. From the viewpoint of efficiency and the like, a so-called continuous process in which raw materials are continuously supplied and polybutylene terephthalate is continuously produced is becoming mainstream. Among these, so-called direct continuous polymerization method using terephthalic acid as a raw material, which has a high raw material basic unit and does not generate harmful methanol, has been attracting attention. However, the polybutylene terephthalate produced by such a method contains solid substances generated from the catalyst substance and foreign substances mixed in the process, which causes the deterioration of the transparency of the product and the cause of foreign object defects (fish eyes). In addition to this, there was a problem that the strength and elongation were reduced.
[0003]
In order to solve this problem, for example, Patent Document 1 and Patent Document 2 propose that a filter is installed in a line connecting a reaction vessel of polybutylene terephthalate. However, since these foreign substances have a particle size distribution and the foreign substances below the filter openings cannot be removed by filtration with a filter, the filter openings can be reduced or drastically reduced to reduce the foreign substances more completely. The only way to reduce the volume is to reduce the filter opening, but the pressure loss in the line increases. Therefore, in order to maintain the flow rate, it is necessary to increase the filtration area of the filter. Even if a certain filtration area is presented from the values, the filtration area is often unrealistic in actual use. In addition, since the filter life is inevitably shortened, the complexity of switching and replacing the filter increases, which has a great adverse effect on productivity and safety. Furthermore, the higher the molecular weight of polybutylene terephthalate and the smaller the filter opening, the higher the shear during the passage, the deterioration due to shearing heat generation is inevitable.
[0004]
On the other hand, it has been found that the amount of foreign matter derived from the catalyst in polybutylene terephthalate can be reduced by reducing the amount of catalyst, but if the amount of catalyst is reduced, the positive reaction rate such as esterification or polycondensation will decrease, resulting in polymerization. The time becomes longer and the time for exposure to high temperature increases, leading to deterioration such as coloring. Further, the decrease in the amount of catalyst causes side reactions such as the formation of tetrahydrofuran, particularly during the initial esterification reaction, resulting in problems such as a decrease in the yield of 1,4-butanediol.
As described above, since foreign matter reduction and productivity are in a contradictory relationship, there has been a strong demand for a technology that fundamentally reduces foreign matter that causes transparency and fish eyes, while maintaining and improving productivity.
[0005]
[Patent Document 1]
JP 2000-336162 A
[Patent Document 2]
JP 2001-270937 A
[0006]
[Problems to be solved by the invention]
An object of the present invention is to provide a method for producing polybutylene terephthalate in which the productivity of polybutylene terephthalate is maintained or improved and at the same time drastically reduced foreign matter in the product, and a film and monofilament comprising the polybutylene terephthalate. It was made as.
[0007]
[Means for Solving the Problems]
As a result of intensive research to solve the above problems, the present inventors have conducted esterification reaction under specific conditions, and installed a specific filter at a specific location to maintain or improve productivity. At the same time, it was found that polybutylene terephthalate with drastically reduced foreign matter in the product can be obtained, and the present invention has been completed.
[0008]
That is, the gist of the present invention is to produce an oligomer by continuously esterifying terephthalic acid and 1,4-butanediol in the presence of a reaction catalyst, and polycondensation reaction of the oligomer to produce polybutylene terephthalate. In the way to
The reaction catalyst is an organic titanium compound or a mixture of an organic titanium compound and an organic tin compound, and the total metal concentration of titanium atoms and tin atoms is 1 to 300 ppm by weight with respect to the raw material terephthalic acid,
An esterification rate is 90% or more, a filter is provided in the flow path of the prepolymer having an intrinsic viscosity of 0.5 or less, and at least a part of a solid having a particle size of 20 μm or more is separated by filtration.
And it exists in the manufacturing method of the polybutylene terephthalate characterized by implementing esterification reaction so that following formula (I) may be satisfy | filled.
P / q ≧ 1500 kJ / m^Three    (I)
(In the formula (I), q (m 3 / sec) represents the total supply amount of raw materials per unit time, and P (kw) represents the stirring power given by the esterification reaction.)
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
The polybutylene terephthalate in the present invention is a polymer having a structure in which a terephthalic acid unit and a 1,4-butanediol unit are ester-bonded, and 50 mol% or more of dicarboxylic acid units are composed of terephthalic acid units, That whose 50 mol% or more consists of a 1, 4- butanediol unit is said. Among them, terephthalic acid units preferably occupy 70 mol% or more, more preferably 80 mol% or more, particularly 95 mol% or more of all dicarboxylic acid units, and 70 mol% or more, more preferably 80 mol of diol units. It is preferable that 1,4-butanediol units occupy% or more, particularly 95 mol% or more. When the amount of terephthalic acid units or 1,4-butanediol units is less than 50 mol%, the crystallization rate of polybutylene terephthalate is lowered, and the moldability is deteriorated.
[0010]
In the present invention, the dicarboxylic acid component other than terephthalic acid is not particularly limited, and examples thereof include phthalic acid, isophthalic acid, 4,4′-diphenyldicarboxylic acid, 4,4′-diphenyletherdicarboxylic acid, and 4,4′-benzophenone dicarboxylic acid. Acid, aromatic dicarboxylic acid such as 4,4′-diphenoxyethanedicarboxylic acid, 4,4′-diphenylsulfonedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexane Alicyclic dicarboxylic acids such as dicarboxylic acid and 1,4-cyclohexanedicarboxylic acid, aliphatic dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid and sebacic acid be able to.
[0011]
In the present invention, the diol component other than 1,4-butanediol is not particularly limited, and examples thereof include ethylene glycol, diethylene glycol, polyethylene glycol, 1,2-propanediol, 1,3-propanediol, polypropylene glycol, and polytetramethylene. Glycol, dibutylene glycol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, aliphatic diol such as 1,8-octanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, Alicyclic diols such as 1,1-cyclohexanedimethylol and 1,4-cyclohexanedimethylol, xylylene glycol, 4,4′-dihydroxybiphenyl, 2,2-bis (4-hydroxyphenyl) propane, bis ( - and aromatic diols such as hydroxyphenyl) sulfone and the like.
[0012]
In the present invention, a hydroxycarboxylic acid such as lactic acid, glycolic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, 6-hydroxy-2-naphthalenecarboxylic acid, p-β-hydroxyethoxybenzoic acid, alkoxycarboxylic acid, etc. Monofunctional components such as acid, stearyl alcohol, benzyl alcohol, stearic acid, benzoic acid, t-butylbenzoic acid, benzoylbenzoic acid, tricarbaric acid, trimellitic acid, trimesic acid, pyromellitic acid, gallic acid, trimethylolethane Trifunctional or higher polyfunctional components such as trimethylolpropane, glycerol and pentaerythritol can be used as the copolymerization component.
[0013]
The polybutylene terephthalate of the present invention preferably has an intrinsic viscosity of 0.6 to 2.0 dL / g measured at 30 ° C. using a mixed solvent of phenol / tetrachloroethane (weight ratio 1/1). It is more preferably 0.7 to 1.8 dL / g, and in particular, 0.9 to 1.6 dL / g is preferable for processing into a film or a monofilament.
[0014]
If the intrinsic viscosity is less than 0.6 dL / g, the mechanical strength of the molded product may be insufficient. If the intrinsic viscosity exceeds 2.0 dL / g, the melt viscosity becomes high and the fluidity deteriorates. As a result, the moldability may be poor.
[0015]
The method for producing polybutylene terephthalate of the present invention is based on a conventional production method. As an example, the dicarboxylic acid component containing terephthalic acid as the main component and the diol component containing 1,4-butanediol as the main component In the presence or absence of an esterification reaction catalyst in a single or a plurality of esterification reaction vessels, usually at a temperature of 180-260 ° C, preferably 200-245 ° C, particularly preferably 210-235 ° C, and usually 10- Esterification reaction product obtained by continuous esterification reaction at a pressure of 133 kPa, preferably 13 to 101 kPa, particularly preferably 60 to 90 kPa, for 0.5 to 5 hours, preferably 1 to 3 hours. In the presence of a polycondensation reaction catalyst, preferably in the presence or absence of a polycondensation reaction catalyst in one or more polycondensation reaction vessels. In particular, the temperature is usually 210 to 280 ° C., preferably 220 to 265 ° C., particularly preferably 230 to 245 ° C., usually 27 kPa or less, preferably 20 kPa or less, particularly preferably 13 kPa or less, and 1 to For example, a polycondensation reaction may be performed for 12 hours, preferably 3 to 10 hours.
[0016]
The resin obtained by the polycondensation reaction is usually transferred from the bottom of the polycondensation reaction tank to a polymer extraction die and extracted in the form of a strand, and while being cooled with water or after water cooling, it is cut with a cutter to form pellets and chips. And so on.
[0017]
Examples of the esterification reaction catalyst in the present invention include antimony compounds such as antimony trioxide, germanium compounds such as germanium dioxide and germanium tetraoxide, titanium alcoholates such as tetramethyl titanate, tetraisopropyl titanate and tetrabutyl titanate, and tetraphenyl. Titanium compounds such as titanium phenolate such as titanate, dibutyltin oxide, methylphenyltin oxide, tetraethyltin, hexaethylditin oxide, cyclohexahexyl distinoxide, didodecyltin oxide, triethyltin hydroxide, triphenyltin hydro Oxide, triisobutyltin acetate, dibutyltin diacetate, diphenyltin dilaurate, monobutyltin trichloride In addition to tin compounds such as tributyltin chloride, dibutyltin sulfide, butylhydroxytin oxide, methylstannic acid, ethylstannic acid, butylstannic acid, etc., manganese compounds, zinc compounds, etc. can be mentioned, among which titanium compounds, A tin compound or a mixture of a titanium compound and a tin compound is preferred, and in particular, a titanium compound, and most preferably tetrabutyl titanate is preferred.
[0018]
If the amount of the catalyst used in the esterification reaction is too large, not only will it cause foreign substances and shorten the filter life, but it will also cause deterioration reaction during heat retention of the polymer and gas generation. Is reduced, and side reactions are likely to occur, so that the weight with respect to the raw material terephthalic acid is preferably 1 to 300 ppm, more preferably 1 to 150 ppm, especially 10 to 100 ppm, and particularly preferably 20 to 60 ppm.
[0019]
In addition, as the polycondensation reaction catalyst, a catalyst added at the time of esterification or transesterification reaction may be used as a polycondensation reaction catalyst, and a new catalyst may not be added. The amount used at that time is not particularly limited, but if it is too much, the above-mentioned problems occur. Therefore, the final polybutylene terephthalate resin usually obtained is 150 ppm or less, preferably 100 ppm or less as a metal atom. Particularly preferably, it may be newly added in the range of 50 ppm or less. However, from the viewpoint of drastically reducing the amount of foreign matter, it is preferable not to add a new catalyst in the polycondensation reaction stage.
[0020]
The amount of these metals can be measured using atomic emission, Induced Coupled Plasma (ICP) or the like after recovering the metal in the polymer by a method such as wet ashing.
[0021]
In the esterification reaction and polycondensation reaction, in addition to the catalyst, orthophosphoric acid, phosphorous acid, hypophosphorous acid, polyphosphoric acid, and phosphorus compounds such as esters and metal salts thereof, sodium hydroxide, sodium benzoate , Reaction aids such as alkali metals or alkaline earth metal compounds such as magnesium acetate and calcium acetate, 2,6-di-t-butyl-4-octylphenol, pentaerythrityl-tetrakis [3- (3 ′, 5 ′ -T-butyl-4'-hydroxyphenyl) propionate], thioether compounds such as dilauryl-3,3'-thiodipropionate, pentaerythrityl-tetrakis (3-laurylthiodipropionate), tri Phenylphosphite, tris (nonylphenyl) phosphite, tris (2,4-di-t-butyl) Nyl) Phosphite and other antioxidants such as phosphorus compounds, paraffin wax, microcrystalline wax, polyethylene wax, long-chain fatty acids such as montanic acid and montanic acid esters and their release agents such as silicone oil Other additives may be present.
[0022]
The esterification reaction tank is not particularly limited as long as it is a reaction tank having a stirring device, and may be any type such as a vertical stirring complete mixing tank, a vertical heat convection mixing tank, and a tower-type continuous reaction tank. Alternatively, a single tank or a plurality of tanks in which the same kind or different kinds of tanks are arranged in series may be used.
A well-known stirrer can be used. In addition to the usual type consisting of a power unit and bearings, shafts, and stirring blades, a high-speed rotating type such as a turbine stator type high-speed rotating stirrer, disk mill type stirrer, rotor mill type stirrer Can also be used.
There is no limitation on the form of stirring, and in addition to the normal stirring method in which the reaction solution in the reaction tank is directly stirred from the top, bottom, side, etc. of the reaction tank, a part of the reaction solution is piped outside the reactor, etc. It is possible to take a method of circulating the reaction liquid by taking it out with a line mixer and the like.
[0023]
Known types of stirring blades can be selected, and specific examples include propeller blades, screw blades, turbine blades, fan turbine blades, disk turbine blades, fouller blades, full zone blades, Max blend blades, and the like.
In the production of the polybutylene terephthalate of the present invention, the total supply amount per unit time of the raw material is q (m^Three/ Sec) and the stirring power to be applied is P (kw), it is necessary to satisfy the relationship of the following formula (I):
P / q ≧ 1500 kJ / m^Three    (I)
More preferably
P / q ≧ 2000 kJ / m^Three
More preferably
P / q ≧ 3000 kJ / m^Three
Especially preferably
P / q ≧ 4000 kJ / m^Three
Optimally
P / q ≧ 5000 kJ / m^Three  It is.
[0024]
The raw material referred to in the present invention refers to a mixture of terephthalic acid and 1,4-butanediol, and is usually supplied to the esterification reaction tank as a slurry. On the other hand, 1,4-butanediol supplied independently from the mixture, 1,4-butanediol collected in the distillation system and returned to the reaction tank, 1,4-butanediol refluxed in the reflux condenser The 1,4-butanediol returning from the outside of the reaction tank into the reaction tank is excluded from the raw materials referred to in the present invention.
[0025]
P / q represents the stirring energy given per unit volume of the feedstock, and the stirring power P can be detected by a method such as installing a torque meter on the stirring shaft or installing a power detector. P / q is 1500 kJ / m^ThreeIf it is less than 1, not only the catalyst-derived foreign matter will increase, but the apparent main reaction rate will slow down and side reactions will emerge, leading to a decrease in the esterification rate.
[0026]
One or a plurality of tanks for carrying out the esterification reaction can be installed. The distinction between the esterification reaction tank and the polycondensation reaction tank in the present invention is that the esterification rate represented by the following formula (III) is The case where it is 90% or less at the inlet is an esterification reaction tank, and the case where it exceeds 90% is a polycondensation reaction tank.
Esterification rate = (saponification value−acid value) × 100 / saponification value (III)
(Here, the acid value is a value obtained by dissolving the oligomer in dimethylformamide and alkali titrating, and the saponification value is a value obtained by alkaline hydrolysis of the oligomer and back titrating with acid.)
[0027]
In producing the polybutylene terephthalate of the present invention, when continuously performing the esterification reaction, the moles of terephthalic acid supplied from the outside to the esterification reaction tank per unit time and 1,4-butanediol are united. It is preferable that the ratio satisfies the following formula (II).
B / T = 2.0 to 4.5 (mol / mol) (II)
(However, B is the number of moles of 1,4-butanediol supplied from the outside to the esterification reaction tank per unit time, and T is the number of moles of terephthalic acid supplied from the outside to the esterification reaction tank per unit time. Indicate)
[0028]
Among these, 2.5 to 4.0, particularly 2.7 to 3.5 is preferable. When B / T is less than 2.0, foreign matters derived from the catalyst tend to increase. When B / T is more than 4.5, not only the thermal efficiency decreases, but also by-products such as tetrahydrofuran increase.
The terephthalic acid supplied to the esterification reaction tank from the outside in the present invention indicates terephthalic acid supplied as a raw material, and is usually supplied in the form of a slurry mixed with 1,4-butanediol or the like.
[0029]
In addition, 1,4-butanediol supplied from the outside to the esterification reaction tank is 1,4-butanediol supplied independently of 1,4-butanediol supplied together with terephthalic acid as a raw slurry. 1,4-butanediol collected in the distillation system and returned to the reaction tank, 1,4-butanediol refluxed in the reflux condenser, etc. This is the sum of butanediol.
[0030]
In the present invention, the esterification rate as defined above is 90% or more, preferably 95% or more, particularly preferably 97% or more, and the intrinsic viscosity is 0.5 or less, preferably 0.1 or more and 0.3 or less. It is necessary to install a filter in the prepolymer flow path. Here, the prepolymer of the present invention is a polybutylene terephthalate precursor having an intrinsic viscosity of 0.5 or less, and includes oligomers.
Most of the catalyst-derived foreign matter is generated in the esterification reaction process, so even if a filter is installed with a low esterification rate, catalyst-derived foreign matter is newly generated and the effect of installing the filter is reduced. To do.
[0031]
In addition, if the filter is installed when the viscosity (molecular weight) has increased, the pressure loss of the line will increase, and in order to maintain the flow rate, the opening of the filter will be increased, the filter's filtration area, piping, etc. Is excessively large, and is subject to high shear when passing through the fluid, so that deterioration of polybutylene terephthalate due to shear heat generation is unavoidable.
[0032]
The filter medium constituting the filter may be any of a metal wind, a laminated metal mesh, a metal nonwoven fabric, a porous metal plate, etc., but a laminated metal mesh or a metal nonwoven fabric is preferable from the viewpoint of filtration accuracy, and the shape of the filter is as follows: Any type of basket type, disc type, leaf disc type, tube type, flat cylindrical type, pleated cylindrical type, etc. may be used. Moreover, in order not to affect the operation of the plant, it is preferable to install a plurality of filters so that they can be switched and used, or to use an auto screen changer.
[0033]
The absolute filtration accuracy of the filter of the present invention is not particularly limited, but if it is too large, the effect of reducing foreign matter in the product is lost, and if it is too small, productivity is lowered and filter replacement frequency is increased. 50 μm, in particular 0.5 to 30 μm, in particular 1 to 20 μm, optimally 1 to 10 μm.
In this specification, the absolute filtration accuracy is expressed as the diameter (μm) of a substantially true spherical object when the substantially true spherical object such as a glass bead is gradually increased when the filter does not pass through the filter.
[0034]
There is no restriction | limiting in particular in the type of the polycondensation reaction tank used for this invention, For example, a vertical stirring polymerization tank, a horizontal stirring polymerization tank, a thin film evaporation type polymerization tank etc. can be mentioned. The number of polycondensation reaction tanks can be one, or a plurality of tanks of the same or different types can be connected in series. It is preferable to select a horizontal stirring polymerization machine having a thin film evaporation function excellent in renewability, plug flow property, and self-cleaning property.
[0035]
Further, the obtained resin granules are usually at a temperature 5 to 50 ° C. lower than the melting point of the resin, preferably 10 to 40 ° C. lower than the melting point under an inert gas atmosphere and / or a reduced pressure of about 13 to 1333 Pa. Thus, it is also possible to carry out a solid phase polycondensation reaction by heat treatment usually for about 5 to 20 hours while flowing so that the granular materials do not stick together.
[0036]
Examples of the embodiment are shown in FIGS.
In FIG. 1, 2 is a fully mixed esterification reaction tank, P1 is a raw material supply pipe, 2a is a vent port provided at the upper part of the reaction tank 2, and 2b is a catalyst supply port provided at the upper part of the reaction tank 2. Reference numeral 2c is a sampling port, and 2d is a 1,4-butanediol supply port. 3 is a fully mixed type first polycondensation reaction tank, 3a is a vent port provided at the top of the first polycondensation reaction tank 2, 4 is a fully mixed type second double condensation reaction tank, and 4a is a second double condensation reaction tank. Vent port provided at the top of the condensation reaction tank 4, 5 is a horizontal triple triple condensation reaction tank having two stirring shafts and a self-cleaning blade in the horizontal direction, and 5a is a third triple condensation reaction tank. 5 is a vent port provided at the upper part of 5, 6 is a filter unit, P <b> 2, P <b> 3 and P <b> 4 are pipes connecting the respective reaction tanks, and P <b> 5 is a polymer extraction pipe. In this case, since the third triple condensation reaction tank 5 has two rotation axes, the same direction and different rotation directions can be selected, but in order to improve the surface renewability, the directions are rather different. Rotation is preferred.
[0037]
FIG. 2 is a mode in which the completely mixed type second double condensation reaction tank in FIG. 1 is replaced with a horizontal reaction tank having a rotation axis in the horizontal direction and having a thin-film distillation ability, and the rotation axis central part where retention easily occurs. The structure has no axis.
FIG. 3 shows an embodiment in which the filter unit in FIG. 2 is attached after the first polycondensation reaction tank, and FIG. 4 shows an embodiment in which the filter unit is attached both after the esterification reaction tank and after the first polycondensation reaction tank. It is.
[0038]
The polybutylene terephthalate of the present invention can be processed into injection molded products such as electric / electronic parts and automobile parts, extruded products such as tubes, films, sheets and monofilaments, fibers and the like by known methods. Can be stretched.
In particular, according to the present invention, the effect of the film or monofilament is remarkable because it can suppress the reduction of the commercial value of the film due to foreign matters and the breakage of the monofilament during stretching.
[0039]
As a method of film formation, for example, a molten resin is extruded into a flat plate shape, and a T-die casting method in which a flat film is drawn continuously by a roll, and a molten resin is continuously extruded from an annular die to adjust the internal air pressure. Air-cooled inflation method that inflates into a balloon shape and cools with cold air, water-cooled inflation method that continuously extrudes from an annular die and cools by applying water while controlling the outer diameter with a metal-made regulating ring, using a roll Examples include the calendering method, but the T-die casting method and the inflation method, which can be melt-extruded without contact with the outside air, are preferable. It is preferable to adjust the temperature.
[0040]
Moreover, it can also be set as a multilayer film using a well-known multilayering apparatus (Multimanihold T die, stack plate die, feed block, multilayer inflation die). The thickness of the film varies depending on the purpose of use, but is usually 10 to 200 μm, and particularly preferably 15 to 150 μm from the viewpoint of the effect of the present invention.
[0041]
Polybutylene terephthalate has a fairly high oxygen barrier property and can prevent oxidative deterioration of its contents even if it is as it is, but semi-finished products such as pastes that require a higher oxygen barrier property and fresh food products for raw consumption For packaging, etc., a resin having lower oxygen permeability than that of polybutylene terephthalate in an environment with a relative humidity of 0%, for example, aliphatic nylon films such as nylon 6 and nylon 66, condensation of aliphatic dicarboxylic acid and aromatic diamine. Or a semi-aromatic nylon typified by a condensate of an aromatic dicarboxylic acid and an aliphatic diamine, or a multilayer structure of a partially saponified product of ethylene-vinyl acetate copolymer (commonly known as EVOH) or an emulsion of vinylidene chloride resin It is also possible to perform processing such as the so-called K-coat.
[0042]
For example, the layer structure for roast ham packaging is polybutylene terephthalate (12.5%) / adhesive resin (6.3%) / 6 nylon (31.2%) / adhesive resin (6.3%) / linear A low density polyethylene (43.7%) and a total thickness of 40 to 80 μm are preferable. In addition,% in () shows the ratio of thickness.
[0043]
Examples of other multilayer structures
PBT / adhesive resin
PBT / adhesive resin / polyethylene resin
PBT / adhesive resin / polypropylene resin
PBT / adhesive resin / polyamide resin / adhesive resin / polyethylene resin or polypropylene resin
PBT / adhesive resin / EVOH resin / adhesive resin / polyethylene resin or polypropylene resin
Polyethylene or polypropylene resin / adhesive resin / PBT / adhesive resin
Etc. The PBT represents polybutylene terephthalate, and specific examples of other resins are as follows.
[0044]
Polyethylene resin: Ultra low density polyethylene, low density polyethylene, linear low density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, and the like.
Polypropylene resin: Homo PP, C4 copolymer PP, C6 copolymer PP, C8 copolymer PP, terpolymer, etc.
Adhesive resin: maleic anhydride-modified polyethylene resin, glycidyl methacrylate copolymer polyethylene resin, glycidyl methacrylate-acrylic acid-copolymer polyethylene resin, and the like.
Polyamide resin: various nylons as described above.
[0045]
When the film is stretched, it is preferably from the vicinity of the glass transition temperature of polybutylene terephthalate to below the melting point, and the stretching ratio is preferably in the range of 1.5 to 5 times in the longitudinal and lateral directions, respectively. If the stretching temperature is too low, stretching breakage does not occur or orientation crystallization does not occur, so that the mechanical properties of the film are not increased, which is not preferable. If the stretching temperature is too high, the film is not preferable because the film is whitened or does not exhibit strength. If the draw ratio is too low, uneven stretching occurs and a film having a uniform thickness cannot be obtained. If it is too high, the film is not stretched and broken. It is important to set the stretching temperature and the stretching ratio within appropriate ranges.
[0046]
For example, in the case of monoaxial stretching of polybutylene terephthalate monolayer, the stretching temperature is 50 to 75 ° C., the stretching ratio is 3 to 6 times, and in the case of single layer or multilayer simultaneous biaxial stretching, the stretching temperature is 50 to 70 ° C. and the stretching ratio is 2.5 × 2. About 5 times to 3.5 × 3.5 times is desirable.
Usually, a stretched film is heat-set at a temperature not lower than the melting temperature and not higher than the melting point in order to develop dimensional stability after the stretching treatment. In the case of stretching polybutylene terephthalate, the heat-set temperature is about 200 ° C. in the case of a monolayer film. In the case of a multi-layer film, the conditions vary considerably depending on the multi-layered resin, but it is advantageous to perform the heat treatment in the range of 80 to 200 ° C.
Further, the film may be prepared using a composition containing polybutylene terephthalate and other resin, and polyethylene terephthalate is preferable as the resin other than polybutylene terephthalate.
[0047]
On the other hand, as a monofilament molding method, for example, a raw material resin is continuously supplied to a single-screw extruder, continuously extruded while being melted from a nozzle at the tip, and once with water or air at about 3 to 50 ° C. The method of cooling and solidifying is mentioned. At this time, if the temperature is too high, the molten resin crystallizes and does not stretch well, or is not preferred because it is whitened. Therefore, cooling with cold water of 5 to 20 ° C. is recommended. Subsequently, the monofilament is reheated in a hot water, steam or air tank set to a temperature near the glass transition temperature of the resin, and preferably, using the difference in speed between the driving rolls installed before and after the tank, preferably 1. Stretching is performed 5 times or more, more preferably 1.8 to 6 times. At this time, if there is a large amount of foreign matter in the polybutylene terephthalate, breakage will be caused. The drawing temperature is about 40 to 280 ° C., and it is important to draw at a low temperature when the yarn diameter is thin and at a high temperature when the yarn diameter is large. Moreover, warm water heating is preferable at a low temperature from the viewpoint of temperature stabilization, steam heating is preferable at around 100 ° C., and heating with hot air is preferable at higher temperatures. This stretching process is usually carried out in 2 to 3 stages, and at that time, it is desirable that the stretching temperature at the second stage from the first stage is equal to or higher than the third stage from the second stage. Subsequently, in order to prevent post-shrinkage, a stable monofilament can be obtained by heat-treating the monofilament stretched with hot air in a glass transition temperature, specifically 60 ° C. to 280 ° C. Such stretching treatment is performed at a temperature below the melting point of polybutylene terephthalate.
[0048]
In addition, in the polybutylene terephthalate single layer film of the present invention, a film obtained by laminating a film made of a polybutylene terephthalate film and other resin, a film or a monofilament made of a composition blended with polybutylene terephthalate and other resin, In order to improve the surface appearance and strength, and prevent troubles such as stretching, the number of foreign matters of 20 μm or more when a 50 μm thick film is formed is 20/100 cm.²It is necessary to use the following polybutylene terephthalate, preferably 10 / cm²Below, especially 5 / 100cm²Below, especially 3 / 100cm²It is as follows. The number of foreign matters of 20 μm or more is 20/100 cm.²If it is more, the object of the present invention cannot be achieved.
[0049]
In addition, the surface of the molded monofilament may be coated with a silicone or fluorine-based lubricant, applied with a surfactant for the purpose of preventing static electricity or imparting flexibility, or dyed or printed with a polyester dye or pigment. I do not care. When forming these films or monofilaments, known additives may be added. For example, when forming a film, it exhibits antioxidant, anti-blocking performance such as phenol, phosphorus, sulfur and amine. Silica, zeolite, talc, glass beads, inorganic particles such as silicone particles, crosslinked organic particles such as crosslinked PMMA and crosslinked polystyrene, calcium stearate and other calcium salts and sodium salts as a lubricant, polyethylene wax, many Examples include esters of polyhydric alcohols, and various colorants and mold release agents. When molding monofilaments, phenolic, phosphorus, sulfur, amine-based antioxidants, for coloring Fluorescent whitening agent for beautiful dyes and colors, plastic for flexibility And oils, UV absorbers for preventing deterioration due to ultraviolet light when used as a monofilament, metal soaps such as calcium stearate and sodium stearate to maintain biting of an extruder and the like.
These additives may be blended with the raw material at the time of molding, or a master batch adjusted to a high concentration in advance may be appropriately diluted at the time of molding.
[0050]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
In Examples and Comparative Examples, polybutylene terephthalate oligomers and polybutylene terephthalate were evaluated by the following methods.
[0051]
(1) Reaction time (average residence time)
A value obtained by dividing the substantial internal volume by the raw material supply amount q was adopted.
(2) Esterification rate of oligomer
It calculated using the acid value and saponification value which were calculated | required as follows.
[Acid value]
The oligomer was dissolved in dimethylformamide and titrated with a 0.1N KOH / methanol solution.
[Saponification value]
The oligomer was hydrolyzed with a 0.5N KOH / ethanol solution and titrated with 0.5N hydrochloric acid.
Esterification rate = (saponification value−acid value) × 100 / saponification value
[0052]
(3) Intrinsic viscosity
Using a mixed solvent of Ubbelohde viscometer and phenol / tetrachloroethane (weight ratio 1/1), at 30 ° C., the prepolymer or polymer solution having a concentration of 1.0 gg / dL, and the number of seconds falling only of the solvent were measured, Obtained from the following equation.
[Η] = ((1 + 4K_Hη_sp)^0.5-1) / (2K_HC)
[0053]
Where η_sp= Η / η₀-1, and
η is the prepolymer or polymer solution falling seconds, η₀Is the number of seconds the solvent falls, C is the prepolymer or polymer solution concentration (g / dL), K_HIs the constant of Haggins. K_HAdopted 0.33.
[0054]
(4) Time to increase filter differential pressure
The pressure before and after the filter was measured, and the time when the difference increased by 0.1 MPa from the initial value was measured. Longer times indicate essentially less foreign material in the prepolymer or polymer.
[0055]
(5) Foreign matter in the film
The resulting polybutylene terephthalate pellets were supplied to a single screw extruder equipped with a T die and the cylinder temperature was set to 270 ° C., melt extruded into a film, and then held at a temperature of 58 to 62 ° C. To obtain a product formed into a film having a thickness of 50 μm, and 10 cm square of the film (100 cm²) Was observed with a stereomicroscope with a magnification of 50 times, the number of foreign matters having nuclei with a size of 20 μm or more at each location was counted, and the average value was calculated.
[0056]
(6) Number of yarn breaks during monofilament molding
The obtained polybutylene terephthalate pellets were charged into a 30 mm single screw extruder, melt extruded at about 260 ° C., and then continuously extruded from a die having 20 1.5 mmφ circular nozzles while being drawn at a drawing speed of 20 m / min. Cooled in 5 ° C water. After that, the first-stage stretching treatment is 2.5 times in hot water at 60 ° C., the second-stage stretching treatment is 1.44 times in hot air at 165 ° C., and the heat treatment is 0.975 times in hot air at 155 ° C. A monofilament having a diameter of about 0.2 mm (490 dTex) was molded for 3 hours and the number of breaks during molding was recorded. A large number of breaks means that there are many foreign substances in the monofilament.
[0057]
(7) Linear filament breaking strength
Using a tensile tester, 10 monofilaments obtained under the same conditions were measured, and the average value was recorded. It shows that the higher the strength is, the less foreign matter and the better quality polybutylene terephthalate is obtained. The dTex in the table is a weight (g) for a monofilament of 10,000 m, which is a small value when the monofilament diameter is small and a large value when the monofilament is large. Since the strength of a monofilament depends on its diameter, it is usually expressed using the normalized value cN / dTex.
[0058]
[Example 1]
FIG. 5 shows a flowchart of this embodiment. In the figure, 1 is a slurry preparation tank, 1a and 1b are raw material supply ports for terephthalic acid and 1,4-butanediol provided in the upper part of the slurry preparation tank 1, 2 is an esterification reaction tank, and 2a is an ester. 2b is a catalyst supply port provided at the upper part of the esterification reaction tank 2, 2c is a sampling port of the esterification reaction tank, and 2d is 1,4-butanediol. Supply port, 3 is a first polycondensation reaction tank, 3a is a vent port provided at the top of the first polycondensation reaction tank 3, 3b is a sampling port of the first polycondensation reaction tank, and 4 is a stirring shaft in the horizontal direction. 4a is a vent port provided in the upper part of the second double condensation reaction tank 4, 7 is an absolute filtration accuracy of 5.0 μm, and a filtration area is 0.31 m.²Filter unit equipped with 3 candle type filters, 9 is a polymer extraction die, 10 is a rotary cutter, M1, M2, M3 and M4 are stirring devices, G1, G2, G3 and G4 are gear pumps, P1, P2 and P3 , P4 is a pipe.
[0059]
A slurry prepared at a ratio of 1.80 moles of 1,4-butanediol with respect to 1.00 moles of terephthalic acid is passed through the pipe P1 by the gear pump G1 from the slurry preparation tank 1, and the esterification rate is 93% in advance. To the esterification reaction tank 2 having a screw type stirrer filled with a polybutylene terephthalate oligomer, and at the same time being fed at 67 L / h, at the same time, tetrabutyl titanate from the catalyst feed port 2b as a titanium amount is 133 ppm with respect to terephthalic acid. Was continuously supplied so that As a catalyst solvent, 1,4-butanediol was used, and its amount was 0.03 mol with respect to 1.00 mol of raw material terephthalic acid supply amount.
[0060]
The esterification reaction tank 2 is a complete mixing type vertical reaction tank provided with a stirring device M2 equipped with a screw type stirring blade having a vertical rotating shaft, and the stirring device M2 is equipped with a device for detecting stirring power. ing.
The internal temperature of the esterification reaction tank 2 is 230 ° C., the pressure is 78 kPa, and the generated water, tetrahydrofuran, and excess 1,4-butanediol are supplied from a vent port 2a connected to a decompressor (not shown). The whole amount was discharged out of the system. At the same time, the esterification reaction was carried out while supplying the purified 1,4-butanediol to the esterification reaction tank 2 through 2d at a ratio of 1.20 mol with respect to 1.00 mol of the feed terephthalic acid (2d) 1,4-butanediol supplied to the esterification reaction tank 2 through 2 is shown as separately supplied 1,4-butanediol in Tables 1 and 2 of the results). At this time, the reaction solution was extracted while controlling the liquid level so that the actual solution in the esterification tank 2 became 100 L. After the system was stabilized, the esterification rate of the oligomer collected from the sampling port 2c was 98%.
[0061]
The first polycondensation reaction tank 3 is also a vertical reaction tank provided with a stirrer M3 having a vertical rotation axis (the stirring blade is a paddle type having a diameter of 510 mm), and has an internal temperature of 245 ° C. and a pressure of 2.7 kPa. The liquid level is controlled so that the liquid becomes 60 L, and the initial polycondensation reaction is performed while extracting the generated water, tetrahydrofuran, and 1,4-butanediol from the vent port 3a connected to a decompressor (not shown). The reaction liquid extracted and extracted was continuously supplied to the second double condensation reaction tank 4 through the filter unit 7. After the system was stabilized, the prepolymer was extracted from the sampling port 3b at the outlet of the gear pump G3, and the intrinsic viscosity was measured to be 0.27.
[0062]
The second double condensation reaction tank 4 is a horizontal reaction tank comprising a plurality of stirring blade blocks and having a stirring blade having no rotating shaft at the center of the stirring rotor. The internal temperature of the reaction tank 4 is 240. For venting in which the liquid level was controlled so that the average residence time was 0.9 hr, and the generated water, tetrahydrofuran, and 1,4-butanediol were connected to a decompressor (not shown). The polycondensation reaction was advanced while being extracted from the mouth 4a. The obtained polymer was continuously extracted in a strand form from the polymer extraction die 9 via the inside of the pipe P4 by the gear pump G4, and was cut by the rotary cutter 10. The obtained polymer had an intrinsic viscosity of 0.95, a titanium content of 100 ppm, and a time required for increasing the differential pressure of the filter was 40 hours.
[0063]
A film was molded using the obtained polybutylene terephthalate and the number of foreign matters was counted. As a result, the number was as small as 1.4. Moreover, when monofilaments were molded using this resin, the breaking strength of the monofilaments obtained was high without any breakage during molding. The results of Examples and Comparative Examples are summarized in Tables 1 and 2.
[0064]
[Table 1]

[0065]
[Table 2]

[0066]
[Example 2]
The same procedure as in Example 1 was conducted except that the amount of the catalyst supplied through 2b was changed as shown in the table. Polybutylene terephthalate with a long time to increase in the differential pressure of the filter and less foreign matters was obtained.
[Example 3]
The same procedure as in Example 1 was conducted except that the amount of 1,4-butanediol supplied through 2d was changed as shown in the table. Polybutylene terephthalate with a long time to increase in the differential pressure of the filter and less foreign matters was obtained.
[0067]
[Example 4]
The same procedure as in Example 3 was performed except that the stirring speed was changed and P / q was changed as shown in the table. Polybutylene terephthalate with a long time to increase in the differential pressure of the filter and less foreign matters was obtained.
[Example 5]
The same procedure as in Example 1 was carried out except that the raw material flow rate was changed, the average residence time in the esterification reaction tank was 1.1 hr, and the stirring rotation speed was changed as shown in the table. Polybutylene terephthalate with a long time to increase in the differential pressure of the filter and less foreign matters was obtained.
[0068]
[Example 6]
The same procedure as in Example 1 was performed except that the reaction temperature was 240 ° C. Polybutylene terephthalate with a long time to increase in the differential pressure of the filter and less foreign matters was obtained.
[Example 7]
The same procedure as in Example 1 was performed except that the absolute filtration accuracy of the filter was changed to 20.0 μm.
[0069]
[Example 8]
The same procedure as in Example 1 was performed except that the filter unit was installed at the position shown in FIG. 6, that is, after the esterification reaction tank.
[Example 9]
The same procedure as in Example 1 was conducted except that the amount of the catalyst supplied through 2b was changed as shown in the table. Polybutylene terephthalate with a long time to increase in the differential pressure of the filter and less foreign matters was obtained.
[0070]
[Example 10]
The same procedure as in Example 1 was conducted except that the amount of the catalyst supplied through 2b was changed as shown in the table. Polybutylene terephthalate with a long time to increase in the differential pressure of the filter and less foreign matters was obtained.
[Comparative Example 1]
The same procedure as in Example 1 was performed except that no filter was used. The amount of foreign matter in the film was large, yarn breakage occurred frequently during monofilament molding, and the linear strength of the monofilament was low.
[0071]
[Comparative Example 2]
The same procedure as in Example 1 was conducted except that the amount of catalyst supplied through 2b was as shown in the table. The time to increase the differential pressure of the filter was extremely short.
[Comparative Example 3]
The same procedure as in Example 1 was carried out except that the rotation speed of stirring was changed and P / q was changed as shown in the table. The time to increase the differential pressure of the filter was extremely short.
[0072]
[Comparative Example 4]
The same procedure as in Example 1 was conducted except that the filter unit was installed at the position shown in FIG. 7, that is, after the second condensation polymerization reaction tank. The experiment was stopped because the viscosity of the fluid (polymer) entering the filter was high and exceeded the designed pressure resistance of the filter.
[0073]
【The invention's effect】
According to the present invention, it is possible to drastically reduce foreign matter in polybutylene terephthalate while maintaining productivity, and to provide a polybutylene terephthalate resin molded product such as a film or a monofilament with extremely little foreign matter. The above effect is great.
[Brief description of the drawings]
FIG. 1 is a schematic view of an apparatus for producing polybutylene terephthalate which is a preferred embodiment of the present invention.
FIG. 2 is a schematic view of an apparatus for producing polybutylene terephthalate, which is another preferred embodiment of the present invention.
FIG. 3 is a schematic view of an apparatus for producing polybutylene terephthalate which is another preferred embodiment of the present invention.
FIG. 4 is a schematic view of an apparatus for producing polybutylene terephthalate which is another preferred embodiment of the present invention.
5 is a schematic view of an apparatus for producing polybutylene terephthalate used in Example 1. FIG.
6 is a schematic view of an apparatus for producing polybutylene terephthalate used in Example 8. FIG.
7 is a schematic view of an apparatus for producing polybutylene terephthalate used in Comparative Example 4. FIG.
[Explanation of symbols]
1 Slurry adjustment tank
1a, 1b Raw material supply port
2 Esterification reaction tank
2a Vent port
2b Catalyst supply port
2c Sampling port
2d 1,4-butanediol supply port
3 First polycondensation reactor
3a Vent port
3b Sampling port
4 Second double condensation reactor
4a Vent port
4b Sampling port
5 Triple condensation reactor
5a Vent port
6, 7, 8 Filter unit
9 Polymer extraction die
10 Rotary cutter
M1, M2, M3, M4 Stirrer
G1, G2, G3, G4 Gear pump
P1 Raw material supply piping
P2, P3, P4 Piping connecting the reaction tanks
P5 Polymer extraction piping

Claims (3)

In the method of producing polybutylene terephthalate by continuously esterifying terephthalic acid and 1,4-butanediol in the presence of a reaction catalyst to obtain an oligomer and polycondensation reaction of the oligomer. An organic titanium compound or a mixture of an organic titanium compound and an organic tin compound, wherein the total metal concentration of titanium atoms and tin atoms is 1 to 300 ppm by weight with respect to the raw material terephthalic acid, and the esterification rate is 90% or more And a filter is provided in the flow path of the prepolymer having an intrinsic viscosity of 0.5 or less, and at least a part of the solid having a particle diameter of 20 μm or more is separated by filtration, and the esterification reaction is represented by the following formula (I): It implements so that it may satisfy | fill, The manufacturing method of polybutylene terephthalate characterized by the above-mentioned.
P / q ≧ 1500 kJ / m ³ (I)
(In the formula (I), q (m ³ / sec) represents the total supply amount of raw materials per unit time, and P (kw) represents the stirring power given by the esterification reaction.)   The method for producing polybutylene terephthalate according to claim 1, wherein the absolute filtration accuracy of the filter is 30 µm or less. 3. The polybutylene terephthalate according to claim 1, wherein the molar ratio of terephthalic acid supplied to the reaction vessel from the outside per unit time and 1,4-butanediol satisfies the following formula (II): Manufacturing method.
B / T = 2.0 to 4.5 (mol / mol) (II)
(However, B is the number of moles of 1,4-butanediol supplied from the outside to the esterification reaction tank per unit time, and T is the number of moles of terephthalic acid supplied from the outside to the esterification reaction tank per unit time. Indicates)

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