JP2022064822A - Method for producing polyester composition excellent in moisture absorption - Google Patents

Abstract

To provide a method for producing moisture absorptive polyester which has a small foreign matter amount in a polyester resin composition, can prevent reduction in operability such as increase in replacement frequency of a spinning pack at the time of spinning and increase in the number of yarn breakage, and can suppress yellowness and oxidation heat generation after washing treatment.SOLUTION: A method for producing copolymerization polyester includes performing esterification reaction or ester exchange reaction using an aromatic dicarboxylic acid or an ester-forming derivative thereof, and diol or an ester-forming derivative thereof, and reacting an esterification reaction product obtained by the esterification reaction or the ester exchange reaction with 10-50 wt.% of polyethylene glycol having a number average molecular weight of 5,000-20,000, in which an amount of a phosphorus compound in the polyethylene glycol is less than 40 ppm as the amount of a phosphorus atom.SELECTED DRAWING: None

Description

The present invention relates to a method for producing a hygroscopic polyester composition.

Polyester fibers are used in a wide range of applications because they are inexpensive and have excellent mechanical properties and a dry feeling. However, since it has poor hygroscopicity, it has problems to be solved from the viewpoint of wearing comfort, such as the generation of stuffiness when the humidity is high in the summer and the generation of static electricity when the humidity is low in the winter.

In order to improve the above-mentioned drawbacks, various proposals have been made so far on a method for imparting hygroscopicity to polyester fibers. As a general method for imparting hygroscopicity, copolymerization of a hydrophilic compound with polyester, addition of a hydrophilic compound, and the like can be mentioned, and polyethylene glycol can be mentioned as an example of the hydrophilic compound.

Further, various methods have been proposed so far for polyester compositions containing polyalkylene glycol containing polyethylene glycol as a constituent component and other additives and the like.

For example, Patent Document 1 proposes a split type polyester fiber using a polyester obtained by copolymerizing 1 to 20% by weight of polyoxyalkylene glycol.

Patent Document 2 proposes a core-sheath type polyester fiber having a polymer obtained by copolymerizing polyethylene glycol having hygroscopicity as a core component.

In Patent Document 3, a poly ether containing a semi-hindered phenolic antioxidant and having a number average molecular weight of 4000 to 30,000 g / mol is copolymerized in an amount of 10 to 60 wt%, and the diol component is 1,4-butanediol. A core-sheath type composite fiber using an ether ester has been proposed. A high molecular weight polyethylene glycol copolymerized polyester containing an antioxidant is fiberized by itself to impart hygroscopicity to the polyester fiber.

On the other hand, Patent Document 4 discloses polybutylene terephthalate having a small amount of foreign matter by supplying a titanium catalyst and a raw material in a specific manner and performing an esterification reaction.

Japanese Unexamined Patent Publication No. 2004-293024 Japanese Unexamined Patent Publication No. 2020-117828 Japanese Patent Publication No. 2019-502036 Japanese Unexamined Patent Publication No. 2004-277719

However, although Patent Document 1 discloses, for example, a copolymerized polyethylene terephthalate obtained by copolymerizing 10 wt% of polyethylene glycol having a molecular weight of 4000 to be used, a higher level of hygroscopicity is required. It is becoming like that.

On the other hand, the methods described in Patent Documents 2 and 3 can obtain a polyethylene glycol copolymerized polyester having excellent hygroscopicity, but it can be obtained because the polyethylene glycol copolymerized polyester is manufactured according to a known polyester manufacturing method. There have been problems such as an increase in the amount of foreign matter in the copolymerized polyester, an effect on yarn characteristics such as the occurrence of yarn spots, yarn breakage during spinning, and a decrease in operability such as an increase in the frequency of replacement of spinning packs.

Therefore, it is conceivable to apply a technique for suppressing the formation of foreign matter, and although Patent Document 4 discloses a method for producing polybutylene terephthalate having a small amount of foreign matter by a continuous polymerization method, since it is a continuous polymerization method, polyethylene is used. It is difficult to apply it to polybutylene terephthalate in which glycol is copolymerized, and there is a problem that the obtained polyester is inferior in hygroscopicity.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, and by suppressing the amount of foreign matter in the copolymerized polyester, it is possible to improve the yarn characteristics and workability at the time of spinning, and the water washing treatment (JIS). It is an object of the present invention to provide a method for producing a hygroscopic polyester composition capable of suppressing yellowing and suppressing heat generation of oxidation after L0217).

The present invention mainly employs the following means in order to solve the above problems.

An esterification reaction or a transesterification reaction is carried out using an aromatic dicarboxylic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof, and the esterification reaction product obtained by the esterification reaction or the transesterification reaction is obtained. In a method for producing a copolymerized polyester in which a polyethylene glycol having a number average molecular weight of 5,000 to 20,000 is reacted in an amount of 10 to 50% by weight, the phosphorus compound content in the polyethylene glycol is less than 40 ppm as a phosphorus atom weight. A method for producing a transesterified polyester composition.

While having high hygroscopicity, since the amount of foreign matter in the polyester and the polyester composition is small, it is possible to prevent an increase in the frequency of replacement of the spinning pack during spinning and a decrease in operability such as an increase in the number of yarn breaks. , A hygroscopic polyester fiber capable of suppressing yellowing and suppressing heat generation of oxidation after washing with water can be obtained.

Hereinafter, the present invention will be described in detail.

The hygroscopicity in the present invention is the difference between the hygroscopicity at a temperature of 30 ° C. and a humidity of 90% RH assuming the temperature and humidity inside the clothes after light exercise, and the hygroscopicity at a temperature of 20 ° C. and a humidity of 65% RH as the outside air temperature and humidity: It can be expressed by ΔMR. The larger the value of ΔMR, the higher the hygroscopicity, and the more comfortable it is to wear when it is used as a fiber or fabric.
The hygroscopicity in the present invention is the difference between the hygroscopicity at a temperature of 30 ° C. and a humidity of 90% RH assuming the temperature and humidity inside the clothes after light exercise, and the hygroscopicity at a temperature of 20 ° C. and a humidity of 65% RH as the outside air temperature and humidity: It can be expressed by ΔMR. The larger the value of ΔMR, the higher the hygroscopicity, and the more comfortable it is to wear when it is used as a fiber or fabric.

From the viewpoint of wearing comfort, the ΔMR of the polyester composition containing the copolymerized polyester obtained by the method for producing a copolymerized polyester of the present invention is preferably 2.0 to 25.0%, and 4.0 to 25. It is more preferably 9.0% or less, further preferably 8.0 to 25.0% or less, particularly preferably 15.0 to 25.0% or less, and most preferably 20.0 to 25.0% or less. When ΔMR is less than 2.0%, the hygroscopicity is low and the feeling of stuffiness in clothes is large. When ΔMR is larger than 25.0%, the melt moldability deteriorates, and the mechanical strength of the molded product may decrease or fluff may occur.

In the method for producing a copolymerized polyester of the present invention, an esterification reaction or a transesterification reaction is carried out using an aromatic dicarboxylic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof, and the esterification reaction or ester is carried out. In a method for producing a copolymerized polyester in which an esterification reaction product obtained by an exchange reaction is reacted with a polyethylene glycol having a number average molecular weight of 5,000 to 20,000 in an amount of 10 to 50% by weight, the amount of phosphorus compound in the polyethylene glycol. Is a method for producing a copolymerized polyester having a phosphorus atom content of less than 40 ppm.

In the method for producing a copolymerized polyester of the present invention, the polyester is a polyester composed of a dicarboxylic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof.

Specific examples of such polyesters include polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polycyclohexylene methylene terephthalate, polyethylene-2,6-naphthalenedicarboxylate, and polyethylene-1,2-bis. (2-Chlorophenoxy) ethane-4,4'-dicarboxylate and the like can be mentioned. Polybutylene terephthalate is preferable for the production method of the present invention from the viewpoint of excellent crystallinity and excellent cutting property at the time of ejection at the end of polymerization.

The method for producing a polyester composition of the present invention comprises dicarboxylic acids such as isophthalic acid, naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, cyclohexanedicarboxylic acid, and 5-sulfoisophthalic acid as dicarboxylic acid components in polyester. The ester-forming derivative may be copolymerized. The amount of the copolymerized dicarboxylic acid component in the total dicarboxylic acid component is preferably 20 mol% or less, more preferably 10 mol% or less.

The method for producing a copolymerized polyester of the present invention includes ethylene glycol, propylene glycol, butanediol, tetramethylene glycol, hexamethylene glycol, diethylene glycol, cyclohexanedimethanol, neopentyl glycol, polypropylene glycol and the like as diol components in these polyesters. The diol compound and its ester-forming derivative may be copolymerized. Butanediol is preferably 80 mol% or more in the total diol component. As a diol component other than butanediol, copolymerization can also be carried out within a range that does not impair the effects of the invention.

Examples of the aromatic dicarboxylic acid include isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, bis (p-carboxyphenyl) methane, anthracendicarboxylic acid, and 4,4'-diphenyl ether. Examples thereof include dicarboxylic acid and 5-sodium sulfoisophthalic acid.

In terms of efficiently producing a polyester composition having excellent heat resistance, mechanical properties and dyeability, terephthalic acid is preferably 50 mol% or more, preferably 90 mol% or more, in the total dicarboxylic acid component. More preferably, it is 100 mol%, which is the most preferable embodiment. It is also a preferred embodiment to use isophthalic acid, 2,6-naphthalenedicarboxylic acid, and 5-sodium sulfoisophthalic acid in combination as an aromatic dicarboxylic acid component other than terephthalic acid.

Examples of the diol include aromatic diols, aliphatic diols, alicyclic diols, and heterocyclic diols. Two or more of these may be used.

Examples of the above aromatic diol include polyoxyethylene- (2.0) -2,2-bis (4-hydroxyphenyl) propane and polyoxyethylene- (2.3) -2,2-bis (4). -Hydroxyphenyl) propane, polyoxyethylene- (2.8) -2,2-bis (4-hydroxyphenyl) propane, and polyoxyethylene- (3.0) -2,2-bis (4-hydroxyphenyl) ) Bisphenol A derivative to which ethylene oxide such as propane is added, and polyoxypropylene- (2.0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene- (2.3) -2,2. -Bis (4-hydroxyphenyl) propane, polyoxypropylene- (2.8) -2,2-bis (4-hydroxyphenyl) propane, and polyoxypropylene- (3.0) -2,2-bis ( 4-Hydroxyphenyl) Examples thereof include bisphenol A derivatives to which propylene oxide such as propane is added.

Examples of the other aliphatic diols described above include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,5-pentanediol, 1,6-hexanediol, and 1,7-heptanediol. Examples thereof include 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, neopentyl glycol, diethylene glycol, polypropylene glycol, polytetramethylene glycol and the like.

Examples of the alicyclic diol include cyclopentanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,2-cyclohexanedimethanol, and 1,4-cyclohexanedimethanol. Two or more of these may be used.

Examples of the above-mentioned heterocyclic diol include isosorbide, isomannide, and isoidet.

From the viewpoint of efficiently producing polybutylene terephthalate having excellent crystallization properties, moldability, heat resistance and mechanical properties, 1,4-butanediol is preferably 50 mol% or more, preferably 90 mol% or more, in the total diol components. It is more preferably mol% or more, and most preferably 100 mol%. It is also a preferred embodiment to use ethylene glycol, 1,3-propanediol and 1,4-cyclohexanedimethanol together as a diol component other than 1,4-butanediol.

The method for producing a copolymerized polyester of the present invention is a method for producing a copolymerized polyester in which polyethylene glycol is copolymerized with the polyester. Copolymerized polyester obtained by copolymerizing polyethylene glycol has no elution of polyethylene glycol in the cleaning step in the higher-order processing step as compared with the case of kneading and mixing polyethylene glycol with polyester, and can maintain high hygroscopicity. It is suitably used as a processed product of.

In the method for producing a copolymerized polyester of the present invention, the polyethylene glycol copolymerized with the polyester has a number average molecular weight of 5000 to 20000, and the copolymerized polyester is copolymerized by 10 to 50% by weight with respect to the weight of the copolymerized polyester. Is the way to get. Here, a specific method for measuring the number average molecular weight and the copolymerization amount of polyethylene glycol in the copolymerized polyester will be described later, but the copolymerized polyester is hydrolyzed with an alkaline aqueous solution and then measured by a gel permeation chromatograph (GPC). can do.

In the method for producing a copolymerized polyester of the present invention, polyethylene glycol having a specific number average molecular weight is copolymerized with the polyester, so that the moisture absorption property becomes extremely large and the processability becomes good. Specifically, when the number average molecular weight of polyethylene glycol copolymerized with polyester is 5000 or more, the hygroscopic performance becomes extremely large. Although the reason for this is not clear, it is considered that when the number average molecular weight is 5000 or more, polyethylene glycol and polyester in the polyester composition of the present invention form a unique structure, and therefore hygroscopicity is extremely high. ing. The number average molecular weight of polyethylene glycol is more preferably 5500 or more, further preferably 6000 or more.

In the method for producing a copolymerized polyester of the present invention, when the number average molecular weight of polyethylene glycol copolymerized with polyester exceeds 20000, the reactivity with polyethylene terephthalate is lowered, the ejection property at the time of polymerization is inferior, and polyethylene glycol is produced. There may be a problem that it dissolves in hot water. The number average molecular weight of polyethylene glycol copolymerized with polyester is more preferably 10,000 or less from the viewpoint of moldability, particularly yarn-making property.

In the method for producing a copolymerized polyester of the present invention, the number average molecular weight of polyethylene glycol copolymerized with polyester can be calculated by the following procedure. Approximately 0.05 g of copolymerized polyester is collected in a sealable vial, 1 mL of 28 wt% aqueous ammonia is added, and the sample is dissolved by heating at 120 ° C. for 5 hours. After allowing to cool, 1 ml of purified water and 1.5 ml of 6M hydrochloric acid are added, and the volume is adjusted to 5 ml with purified water. After centrifugation, the mixture is filtered through a 0.45 μm filter, and the number average molecular weight of the one-ended closed polyalkylene oxide compound contained in the filtrate is measured by gel permeation chromatography (GPC). The number average molecular weight of polyethylene glycol, which is a copolymerization component in the present invention, refers to a value obtained by GPC in terms of standard polyethylene glycol.

In the method for producing a copolymerized polyester of the present invention, the polyester is a polyester copolymerized with polyethylene glycol, and the copolymerization amount of the polyethylene glycol copolymerized with the polyester is 10 to 50% by weight based on the weight ratio of the copolymerized polyester. .. When the copolymerization amount of polyethylene glycol is less than 10% by weight, the hygroscopicity of the obtained copolymerized polyester is small, the hygroscopicity is about the same as that of the polyester not copolymerized with polyethylene glycol, and the feeling of stuffiness in clothes is increased. From the viewpoint of obtaining high hygroscopicity, the copolymerization amount of polyethylene glycol is preferably 10% by weight or more, more preferably 20% by weight or more, further preferably 30% by weight or more, and particularly preferably 40% by weight or more. .. Further, from the viewpoint of heat resistance and melt moldability, for example, spinnability, the amount of polyethylene glycol added needs to be 50% by weight or less. If it exceeds 50% by weight, the obtained copolymerized polyester may not be able to withstand use in a high temperature range, or the mechanical strength of the molded product may decrease.

In the method for producing a copolymerized polyester of the present invention, the copolymerization amount of polyethylene glycol copolymerized with the polyester can be calculated by the following procedure. Approximately 0.05 g of copolymerized polyester was collected in a measuring tube of a nuclear magnetic resonance apparatus (NMR), and 1 g of deuterated 1,1,1,3,3,3-hexafluoro-2-isopropanol (HFIP) was added and dissolved. do. By performing 1H-NMR measurement on this solution, the amount of copolymerization of polyethylene glycol copolymerized with the polyester composition can be calculated.

Since the copolymerized polyester in the method for producing a copolymerized polyester of the present invention is a polymer obtained by a condensation reaction containing a dicarboxylic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof as main components, the dicarboxylic acid. Alternatively, it can be produced by subjecting the ester-forming derivative and the diol or the ester-forming derivative thereof to an esterification reaction or an ester exchange reaction, and then a polycondensation reaction.

The time for adding the copolymerized polyethylene glycol is, for example, before the esterification reaction or the ester exchange reaction, from the time when the esterification reaction or the ester exchange reaction is substantially completed until the polycondensation reaction is started. It is added at any stage, such as after substantially completion. However, from the viewpoint of obtaining a copolymerized polyester having excellent hygroscopicity, it is preferable to add polyethylene glycol from the time when the esterification reaction or the transesterification reaction is substantially completed until the polycondensation reaction is started.

In the method for producing a copolymerized polyester of the present invention, it is preferable to carry out an esterification reaction using an aromatic dicarboxylic acid and a diol containing 50 mol% or more of 1,4-butanediol.

The method for producing a copolymerized polyester of the present invention is an esterification reaction product (oligomers) obtained by an esterification reaction or a transesterification reaction using an aromatic dicarboxylic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof. ) Is transferred to a polymerization can, and a transesterification reaction with polyethylene glycol is carried out to obtain a copolymerized polyester. At this time, 1,4-butanediol should be 50 mol% or more in the total diol component from the viewpoint that polybutylene terephthalate having excellent crystallization characteristics, moldability, heat resistance and mechanical properties can be efficiently produced. preferable. Further, in the polyethylene glycol, the amount of foreign matter in the obtained copolymerized polyester is reduced, and it is possible to prevent a decrease in operability such as an increase in the frequency of replacement of the spinning pack during spinning and an increase in the number of yarn breaks. The amount of the phosphorus compound contained in the above is less than 40 ppm as the atomic weight of phosphorus. 30 ppm or less is more preferable, 20 ppm or less is particularly preferable, and 10 ppm or less is particularly preferable, and 0 ppm, that is, a phosphorus compound is contained, from the viewpoint that foreign matter formation can be further suppressed and the frequency of pack replacement during spinning can be reduced. Most preferably not. When the amount of the phosphorus compound contained in the polyethylene glycol is 40 ppm or more as the phosphorus atomic weight, the frequency of replacement of the spinning pack at the time of spinning increases and the yarn breakage occurs frequently, which is inefficient.

In the method for producing a copolymerized polyester of the present invention, the phosphorus atomic weight in polyethylene glycol can be detected by the following procedure. First, wet decomposition is performed to make the sample into a solution. Take about 0.5 g of polyethylene glycol in a 100 mL Erlenmeyer flask, add 10 mL of sulfuric acid, and heat to 250 ° C. on a sand bath. After adding 1 mL of perchloric acid, heat to 300 ° C., and further add 1 mL of perchloric acid. Heat at 350 ° C. for 10 minutes until the solution becomes colorless and transparent, and reflux the sulfuric acid for 3 minutes. After cooling, the treatment liquid is transferred to a 250 mL volumetric flask, titrated and neutralized with a 40% NaOH aqueous solution, and the volume is adjusted to 250 mL with pure water. To 10 mL of the obtained neutralizing solution, 2 mL of molybdenum blue coloring solution is added, and the volume is adjusted to 20 mL with pure water. After 15 minutes, the absorbance was measured at 720 nm with an absorptiometer. A calibration curve using phosphoric acid was prepared in advance, the amount of phosphoric acid in the sample was calculated, and the amount of phosphorus atom was further calculated.

The method for producing a copolymerized polyester of the present invention is characterized in that the phosphorus atom in the polyethylene glycol is derived from phosphate. Conventionally, as a condition for producing polyethylene glycol, a method of using an alkali metal as a polymerization catalyst and adding phosphoric acid as a catalyst deactivating agent in the latter stage of polymerization has been adopted, so that phosphate is present in polyethylene glycol. Was there. However, the inventors have found that the phosphate in polyethylene glycol tends to aggregate when heated and becomes a foreign substance in the copolymerized polyester using the polyethylene glycol as a raw material. Therefore, the phosphorus atom content derived from the phosphate of the polyethylene glycol is preferably less than 40 ppm, more preferably 30 ppm or less, still more preferably 20 ppm or less, from the viewpoint of suppressing the formation of foreign substances in the copolymerized polyester. It is particularly preferably 10 ppm or less, and most preferably 0 ppm, that is, it does not contain phosphate.

In the method for producing a copolymerized polyester of the present invention, the polyethylene glucol contains an alkali metal compound used during polyethylene glycol polymerization, and the amount of the alkali metal compound is preferably 100 ppm or less as the alkali metal atom weight. When the antioxidant is kneaded with the copolymerized polyester made from the polyethylene glycol, foreign substances are formed from the alkali metal compound contained in the polyethylene glycol, and the frequency of replacement of the spinning pack during spinning increases. , It was found that the operability such as the increase in the number of thread breaks is reduced. Therefore, it is possible to suppress the formation of foreign matter in the copolymerized polyester, and it is possible to prevent an increase in the frequency of replacement of the spinning pack during spinning and a decrease in operability such as an increase in the number of yarn breaks. The amount of the alkali metal compound is preferably 100 ppm or less, more preferably 70 ppm or less, and particularly preferably 40 ppm or less as the alkali metal atom weight.

In the method for producing a copolymerized polyester of the present invention, the alkali metal atom is an atom belonging to Group 1 in the periodic table excluding hydrogen, and refers to sodium, potassium, lithium, rubidium, cesium, and franchium, and forms foreign substances. Potassium and sodium, which have low basicity as an alkali metal compound and low activity for forming foreign substances, are preferable, and sodium is particularly preferable. As for the amount of potassium atom contained in the polyethylene glycol, the amount of the potassium compound in the polyethylene glycol is potassium because it can suppress the formation of foreign matter when the antioxidant is kneaded with the copolymerized polyester made from the polyethylene glycol. The atomic weight is preferably 100 ppm or less, more preferably 60 ppm or less, and particularly preferably 10 ppm or less. Further, as the sodium atomic weight contained in the polyethylene glycol, the sodium compound amount in the polyethylene glycol is preferably 100 ppm or less, more preferably 70 ppm or less, from the viewpoint of suppressing the formation of foreign substances. It is preferably 40 ppm or less, and particularly preferably 40 ppm or less. Examples of the alkali metal compound include alkali metal hydroxides, alkali metal acetates and carbonates, and phosphates. Acetate is preferable from the viewpoint that it is low in basicity, can suppress the formation of foreign substances, and can suppress the hydrolysis of the copolymerized polyester using the polyethylene glycol as a raw material.

In the method for producing a copolymerized polyester of the present invention, the esterification reaction involves a molar ratio of a diol component containing 50 mol% or more of 1,4-butanediol or an ester-forming derivative thereof to a terephthalic acid or an ester-forming derivative of terephthalic acid. It is preferable to carry out under the condition that is greater than 1.2 and 2.5 or less. The upper limit of the molar ratio is 1. From the viewpoint of the effect of suppressing the amount of by-product THF generated by the cyclization of 1,4-butanediol, efficient production, and shortening the reaction time of the polycondensation reaction. It is more preferably 8 or less, and particularly preferably 1.6 or less.

Further, in the esterification reaction, an additional diol component may be added from the viewpoint of efficiently advancing the reaction. The additional addition of the diol component may be carried out after the completion of the esterification reaction or the transesterification reaction and before the start of the polycondensation reaction, but from the viewpoint of shortening the polymerization time, the start of the polycondensation reaction after the start of the esterification reaction. It is more preferable to carry out at any of the stages up to. The additional addition of the diol component may be carried out a plurality of times, but from the viewpoint of operability, it is preferable to carry out the addition once at any stage from the start of the esterification reaction to the start of the polycondensation reaction.

Further, the esterification reaction contains 50 mol% or more of aromatic dicarboxylic acid and 1,4-butanediol by carrying out an initial polymerization reaction under reduced pressure in the latter stage of the esterification reaction after a predetermined esterification reaction time has elapsed. The Mp of the oligomer obtained by the esterification reaction using a diol is 1250 or more. The initial polymerization reaction is preferably carried out under a reduced pressure of 70 kPa or less, more preferably 35 kPa or less, and particularly preferably 10 kPa or less. The reaction time is preferably 30 minutes or more from the viewpoint of increasing the molecular weight of the esterification reaction product (oligomer), and preferably 60 minutes or less from the viewpoint of productivity.

Further, it is preferable to carry out the esterification reaction under a reduced pressure of 30 kPa or more and 95 kPa or less. When the reaction pressure of the esterification reaction is 30 kPa or more, the strength of the yarn using the obtained polyester can be further improved. From the viewpoint that the strength of the yarn using the obtained polyester can be further improved, the reaction pressure of the esterification reaction is preferably 60 kPa or more, more preferably 80 kPa or more, and 85 kPa or more. Is more preferable. On the other hand, when the pressure of the esterification reaction or the transesterification reaction is 95 kPa or less, the reaction time of the esterification reaction can be further shortened.

Further, a reaction catalyst can be used for the esterification reaction or the transesterification reaction because the reaction time can be shortened. Examples of the reaction catalyst include titanium compounds and / or tin compounds. In the present invention, it is preferable to use a titanium compound from the viewpoint that the reaction time can be further shortened.

In the method for producing a copolymerized polyester of the present invention, the titanium compound used as a reaction catalyst during the esterification reaction includes the general formula (R ₁ O) nTi (OR ₂ ) (4-n) (however, in the formula, R ₁ and R ₂ each independently represent an aliphatic, alicyclic or aromatic hydrocarbon group having 1 to l0 carbon atoms, and n represents a titanium represented by a number from 0 to 4 (including a fraction). Acid esters or condensates thereof are preferred.

Specific examples of the titanium compound represented by the above general formula include methyl ester of titanium acid, tetra-n-propyl ester, tetra-n-butyl ester, tetraisopropyl ester, tetraisobutyl ester, and tetra-t-butyl ester. Examples thereof include cyclohexyl esters, phenyl esters, benzyl esters and trill esters, or mixed esters thereof. Two or more of these may be used. Among these, tetra-n-propyl ester of titanium acid, tetra-n-butyl ester and tetraisopropyl ester are preferable, and tetra-n-butyl ester of titanium acid is particularly preferable from the viewpoint that polyester can be produced more efficiently. Is preferably used.

The amount of these titanium compounds added is preferably in the range of 0.02 to 0.2% by weight with respect to the produced polyester from the viewpoint that the polyester can be produced more efficiently.

Specific examples of the tin compound include dibutyltin oxide, methylphenyl tin oxide, tetraethyl tin oxide, hexaethyl ditin oxide, cyclohexahexyl ditin oxide, didodecyl tin oxide, triethyl tin hydroxide, triphenyl tin hydrooxide, and tri. Examples thereof include isobutyl tin acetate, dibutyl tin diacetate, diphenyl tin dilaurate, monobutyl tin trichloride, dibutyl tin dichloride, tributyl tin chloride, dibutyl tin sulfide and butyl hydroxy tin oxide. Two or more of these may be used. Among these, monoalkyltin compounds are preferably used because polybutylene terephthalate can be produced more efficiently.

Further, as another tin compound, stannonic acid can also be used. For example, alkyl stannon acids such as methyl stannon acid, ethyl stannon acid and butyl stannon acid are preferably used. Two or more of these may be used.

The amount of these tin compounds added is preferably in the range of 0.03 to 0.2% by weight with respect to the produced polyester from the viewpoint that the polyester can be produced more efficiently.

The timing of adding these reaction catalysts may be any time before the end of the esterification reaction, but it is more preferable to add these reaction catalysts before the start of the esterification reaction from the viewpoint of further shortening the reaction time.

In the method for producing a copolymerized polyester composition of the present invention, the reaction temperature of the esterification reaction or the transesterification reaction is preferably 140 ° C. or higher, more preferably 150 ° C. or higher, from the viewpoint that the reaction time can be further shortened. , 160 ° C. or higher is more preferable. The reaction temperature of the esterification reaction is preferably 290 ° C. or lower, more preferably 280 ° C. or lower, and even more preferably 240 ° C. or lower.

Next, the polycondensation reaction in the present invention will be described.

In the method for producing a copolymerized polyester of the present invention, in the polycondensation reaction, a reaction catalyst can be separately added as needed in order to effectively proceed with the polycondensation reaction. For example, antimony compounds such as antimony trioxide and antimony acetate, zirconia compounds such as zirconium tetra-n-butoxide, the titanium compound and the tin compound are produced from 0.01 to 0. It is preferable to add it in the range of 15% by weight, and it is particularly preferable to use a titanium compound.

The addition time of these reaction catalysts may be any time as long as it is before the completion of the polycondensation reaction, but it is preferable to add these reaction catalysts after the completion of the esterification reaction and before the start of the polycondensation reaction from the viewpoint of shortening the reaction time.

In the method for producing a copolymerized polyester of the present invention, the copolymerized polyester is a polyester obtained by copolymerizing polyethylene glycol. Compared with the case of kneading polyethylene glycol, polyethylene glycol does not elute in the cleaning step in the higher processing step, and high hygroscopicity can be maintained, so that it is suitably used as a processed product such as fiber.

In the method for producing a copolymerized polyester of the present invention, it is preferable to charge polyethylene glycol in a polymerization tank in advance and transfer the esterification reaction product (oligomer) when the temperature of the polymerization tank is 210 ° C. or lower. The temperature is preferably 210 ° C. or lower, more preferably 200 ° C. or lower, from the viewpoint that decomposition of polyethylene glycol can be suppressed and the polycondensation reactivity does not decrease.

The temperature of the polymerization tank at the time of transferring the esterification reaction product is synonymous with the temperature of the polyethylene glycol previously charged in the polymerization tank.

In the method for producing a copolymerized polyester of the present invention, it is preferable to charge polyethylene glycol in a polymerization tank in advance and melt the polyethylene glycol under humidity-controlled air or nitrogen having a moisture content of 0.01% or less. It is preferable to melt the polyethylene glycol under air or nitrogen having a moisture content of 0.01% or less because the decomposition of the polyethylene glycol can be suppressed and the polycondensation reactivity does not decrease.

In the method for producing a copolymerized polyester of the present invention, it is preferable to add a phenolic antioxidant at the time of polymerization because the frequency of changing the spinning pack at the time of spinning can be reduced. The type of phenolic antioxidant is not particularly limited, but from the viewpoint of cost, pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenol) propionate) (BASF, Irganox (registered trademark)) It is preferable to add 1010 (IR1010)). The amount of IR1010 added is preferably in the range of 0.15 to 0.50% by weight (5.0 to 17.0 mmol / kg), preferably 0.25 to 0.50% by weight (8.0). ~ 17.0 mmol / kg) is more preferable, and 0.35 to 0.50% by weight (11.5 to 17.0 mmol / kg) is most preferable. When the addition amount is less than 0.15% by weight (5.0 mmol / kg), the effect of reducing the frequency of changing the spinning pack during spinning tends not to be exhibited. If the amount added is more than 0.50% by weight (17.0 mmol / kg), the obtained yarn tends to turn yellow in the presence of nitrogen oxides.

In the method for producing a copolymerized polyester of the present invention, the polycondensation reaction is preferably carried out under a reduced pressure condition of a reaction pressure of 133 Pa or less from the viewpoint that the polycondensation reaction time can be shortened.

In the polycondensation reaction, the polycondensation conditions used in the production of ordinary polyesters, such as a batch method or a continuous method, can be applied as they are. For example, the reaction temperature of the polycondensation reaction is preferably 230 ° C. or higher, more preferably 240 ° C. or higher. The reaction temperature of the polycondensation reaction is preferably 260 ° C. or lower, more preferably 255 ° C. or lower.

In the method for producing a copolymerized polyester of the present invention, solid phase polymerization may be further carried out in order to obtain a polyester raw material having a large molecular weight and a high intrinsic viscosity. The solid phase polymerization is generally carried out under reduced pressure or in a nitrogen atmosphere, but is not particularly limited in the present invention. The solid phase polymerization temperature is preferably 180 ° C. or higher, more preferably 185 ° C. or higher, from the viewpoint of reaction rate and productivity. On the other hand, 240 ° C. or lower is preferable, and 230 ° C. or lower is more preferable, from the viewpoint of suppressing fusion between polyester chips. The solid phase polymerization temperature can be arbitrarily set within the above range. As a general tendency, when the polymerization is carried out at a low temperature, the reaction rate decreases and the time for increasing the expected intrinsic viscosity becomes longer, but the maximum reached intrinsic viscosity increases. On the contrary, when the polymerization temperature is raised, the reaction rate increases, but at the same time, the deterioration reaction proceeds, so that the maximum intrinsic viscosity becomes low.

In the method for producing a copolymerized polyester of the present invention, for example, phosphoric acid, phosphoric acid, hypophosphoric acid, pyrophosphoric acid, phosphoric acid triamide, monoammonium phosphate, trimethyl phosphate, dimethyl phosphate, diphenyl phosphate, phosphorus. By blending a phosphorus compound such as triphenyl acid, diphenyl phosphite, triphenyl phosphite and dimethylphenyl phosphonate, a preferable effect that the color tone of the obtained copolymerized polyester is remarkably improved can be obtained. These phosphorus compounds are preferably added during the polycondensation reaction, for example, in the method for producing a copolymerized polyester.

In the method for producing a copolymerized polyester of the present invention, particles are added for the purpose of reducing friction with various guides, rollers and other contact objects in the molding process, improving process passability, and adjusting the color tone of the product. It doesn't matter. Any of the conventionally known particles can be used as the type of the particles. Specifically, for example, inorganic particles such as silicon dioxide, titanium dioxide, calcium carbonate, barium sulfate, aluminum oxide and zirconium oxide, and organic polymer particles such as crosslinked polystyrene can be used. Among these particles, titanium dioxide particles are preferable because they have good dispersibility in the polymer and are relatively low in cost. Titanium dioxide particles are produced by various wet and dry methods, and if necessary, are subjected to pretreatment such as pulverization and classification, and then added to the reaction system of the copolymerized polyester. The addition of the particles to the copolymerized polyester reaction system may be performed at any stage, but it is preferable to add the particles after substantially completing the esterification reaction or the transesterification reaction because the dispersibility in the polymer is improved. The amount of particles added to the polymer and the particle size vary depending on the application and are not particularly limited, but are 0.01 to 10% by weight based on the copolymerized polyester, the average particle size is 0.05 to 5 μm, and the particle size is 4 μm. When the number of the above coarse particles is in the range of 1000 particles / 0.4 mg or less, the process passability and the color tone are particularly good, which is preferable.

Further, in the method for producing a copolymerized polyester of the present invention, a blue-based adjusting agent, a red-based adjusting agent, and a purple-based adjusting agent may be added as color tone adjusting agents at the time of polymerization. The color tone adjuster is a dye used for a resin or the like, and specifically, a blue color tone adjuster such as SOLVENT BLUE 104, SOLVENT BLUE 122, SOLVENT BLUE 45, SOLVENT RED 111, etc. in COLOR INDEX GENERIC NAME. , SOLVENT RED 179, SOLVENT RED 195, SOLVENT RED 135, PIGMENT RED 263, VAT RED 41 and other red color tone adjusters, DESPERSE VIOLET 26, SOLVENT VIOLET 13, SOLVENT VIOLET color tone 37 A modifier can be mentioned. Among them, SOLVENT BLUE 104, SOLVENT BLUE 45, SOLVENT RED 179, SOLVENT RED 195, SOLVENT RED 135, which do not contain halogens that easily cause equipment corrosion, have relatively good heat resistance at high temperatures, and have excellent color development. SOLVENT VIOLET 49 is preferably used. Further, one kind or a plurality of kinds of these color tone adjusting agents can be used depending on the purpose. In particular, it is preferable to use one or more of each of the blue-based adjusting agent and the red-based adjusting agent because the color tone can be finely controlled. Further, in this case, when the ratio of the blue-based adjusting agent to the total amount of the color tone adjusting agent to be added is 50% by weight or more, the color tone of the obtained copolymerized polyester is particularly good, which is preferable. Finally, the total content of the color tone adjusting agent with respect to the copolymerized polyester is preferably 30 ppm or less. If it exceeds 30 ppm, the transparency of the copolymerized polyester may decrease or the color may become dull. The content can be calculated from the structure specification of the color tone adjusting agent and the ratio of the constituent parts of the color tone adjusting agent by a nuclear magnetic resonance apparatus (NMR).

In the method for producing a copolymerized polyester of the present invention, after obtaining the copolymerized polyester, a phenolic antioxidant represented by the following chemical formula (1) (hereinafter, may be abbreviated as a phenolic antioxidant) is used together. It is preferable to include a step of adding to the polymerized polyester (note that a composition to which an additive or the like is added after the polymerization is also referred to as a copolymerized polyester composition).

In the above formula, R ₁ , R ₂ , and R ₃ represent any of a hydrocarbon group, a hydroxyl group, and a hydrogen atom.

Specific examples of the phenolic antioxidant to be added in the method for producing a copolymerized polyester of the present invention include 2,6-di-t-butyl-p-cresol, butylhydroxyanisole, and 2,6-di-. t-butyl-4-ethylphenol, stearyl-β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2,2'-methylenebis (4-methyl-6-t-butylphenol), 2 , 2'-methylenebis (4-ethyl-6-t-butylphenol), 4,4'-butylidenebis (3-methyl-6-t-butylphenol), 3,9-bis {1,1-dimethyl-2-{ β- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy} ethyl} 2,4,8,10-tetraoxaspiro {5,5} undecane, 1,1,3-tris (2) -Methyl-4-hydroxy-5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, bis {3,3'-bis- (4'-hydroxy-3'-t-butylphenyl) butyric acid} glycol ester, tocopherol, pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4) -Hydroxyphenol) propionate), bis [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionic acid] [ethylenebis (oxyethylene)], 1,3,5-tris [[4- (1,1-Dimethylethyl) -3-hydroxy-2,6-dimethylphenyl] methyl] -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione and the like can be mentioned. , Not limited to these. Only one of these phenolic compounds may be used, or two or more thereof may be used in combination. From the viewpoint of high oxidative decomposition inhibitory effect, reduction of the amount of yellow quinone compound produced during water washing treatment, and high yellowing inhibitory effect, bis [3- (3-t-butyl-4-) Hydroxy-5-methylphenyl) propionic acid] [ethylenebis (oxyethylene)] (BASF, IRGANOX® 245), 3,9-bis {1,1-dimethyl-2- {β- (3-) t-butyl-4-hydroxy-5-methylphenyl) propionyloxy} ethyl} 2,4,8,10-tetraoxaspiro {5,5} undecane (made by ADEKA, Adecastab® AO-80), 1 , 3,5-Tris [[4- (1,1-dimethylethyl) -3-hydroxy-2,6-dimethylphenyl] methyl] -1,3,5-triazine-2,4,6 (1H, 3H) , 5H) -Trion (manufactured by RIANINLON CORPORATION, THANOX1790) can be suitably adopted.

The type of phenolic antioxidant contained in the copolymerized polyester composition obtained by the production method of the present invention can be identified by the following procedure. After dissolving about 1 g of the copolymerized polyester composition in 20 mL of HFIP, 40 mL of toluene is added. Then, 60 mL of methanol is added to precipitate. The prepared solution can be filtered through a 0.45 μm filter and the solvent removed from the filtrate using an evaporator to give an antioxidant. The obtained antioxidant is placed in an NMR measurement tube, and 1 g of deuterated HFIP is added and dissolved. By performing 1H-NMR measurement on this solution, the structure of the phenolic antioxidant contained in the polyester composition can be clarified and the type can be identified.

In the method for producing a copolymerized polyester of the present invention, it is preferable to add 10.0 to 200.0 mmol / kg (0.5 to 8.0% by weight) of the above-mentioned phenolic antioxidant. When the amount of the phenolic antioxidant added is less than 10 mmol / kg (0.5% by weight), the composite fiber made of the copolymerized polyester composition obtained by the present invention is washed with water (JIS L0217-1995). ) Decreases the heat resistance to oxidation, and heat generation of oxidation occurs in less than 90 hours. When the amount of the phenolic antioxidant added is more than 200.0 mmol / kg (8.0% by weight), the orientation of the fibers using the copolymerized polyester composition is suppressed, so that the fiber strength is lowered and the knitting is performed. , Frequent thread breakage in the weaving process and deterioration of quality due to fluffing during use occur. From the viewpoint of heat resistance to oxidation and fiber strength, the amount of the phenolic antioxidant added is more preferably 70.0 to 200.0 mmol / kg (3.0 to 8.0% by weight), and 120.0 to 200. 0.0 mmol / kg (5.0 to 8.0% by weight) is particularly preferable.

The oxidation heat resistance test of the composite fiber using the above copolymerized polyester composition is carried out by the following procedure. Samples subjected to water washing treatment (JIS L0217-1995) are stacked to a depth of 25 mm in a cylindrical container, and a thermocouple is installed in the center thereof. Further, the samples are stacked and filled in the cylindrical container without any gap. A cylindrical container filled with a sample is placed in a constant temperature dryer set at 150 ° C., and the time at which oxidative heat generation starts is measured. If the oxidative heat generation start time was 100 hours or more, it was passed, if it was 90 hours or more, it was good, and if it was less than 90 hours, it was rejected.

The content of the phenolic antioxidant contained in the copolymerized polyester composition obtained by the production method of the present invention can be calculated by the following procedure. After dissolving about 1 g of the copolymerized polyester in 20 mL of HFIP, 40 mL of toluene is added. Then, 60 mL is added with methanol to precipitate. The prepared solution is filtered through a 0.45 μm filter, the obtained filtrate is used as a measurement sample, and HPLC measurement is performed to calculate the content of the phenolic antioxidant contained in the polyester composition.

In the method for producing a copolymerized polyester of the present invention, it is preferable to further include a step of adding a phosphorus-based antioxidant. By adding a phosphorus-based antioxidant, the deactivation of phenol due to the hypochlorous acid-based bleach used in the water washing treatment (JIS L0217-1995) is suppressed, and high oxidation heat resistance even after the water washing treatment. Is expressed. The phosphorus-based antioxidant added in the method for producing a polyester composition of the present invention is not particularly limited as long as it is a compound having a phosphorus element. Specifically, triphenylphosphite, tris (2,4-t-butylphenyl) phosphite, bis [2,4 bis (1,1-dimethylethyl) -6-methylphenyl] ethyl ester hypophosphate, Bis (2,4-t-butylphenyl) pentaerythritoldiphosphite, tetrakis (2,4-di-t-butylphenyl) [1,1 biphenyl] -4,4'-diylbisphosphonite, tetra (C12-C15 Alkyl) -4,4'-isopropyridenediphenyldiphosphite, 3,9-bis (2,6-t-butyl-4-methylphenoxy) -2,4,8,10-tetraoxa-3 , 9-Diphosphaspiro [5,5 undecane], 1,1'-biphenyl-4,4'-diylbis [bis phosphonate (2,4-di-t-butylphenyl)], tri (C12-C18 alkyl) Examples include phosphite. Only one of these phosphorus-based antioxidants may be used, or two or more thereof may be used in combination. Among them, Tris (2,4-t-butylphenyl) phosphite (BASF, IRGAFOS® 168), 3,9-bis (2,6-t-butyl-4-methylphenoxy) -2, 4,8,10-Tetraoxa-3,9-diphosphaspiro [5,5 undecane] (ADEKA, Adecastab® PEP-36), Tetra (C12-C15 alkyl) -4,4'-isopropyridendiphenyldi Phosphite (manufactured by Johoku Kagaku, JA-805), 1,1'-biphenyl-4,4'-diylbis [bisphosphonate (2,4-di-t-butylphenyl)] (manufactured by Clarianto Chemicals, HOSTANOX P) -EPQ), trioleyl phosphite (manufactured by Johoku Kagaku, JP-318-O), tristearyl phosphite (manufactured by Johoku Kagaku, JP-318E) are suitable because they have good oxidative decomposition resistance after water washing treatment. From the viewpoint of suppressing yellowing after washing with water, P-EPQ, PEP-36, JP-318-O or JP-318E are more preferable. From the viewpoint of suppressing bleed-out when the chips are dried before spinning, and as will be described later, it is possible to suppress the formation of foreign substances derived from phosphorus-based antioxidants, and operability such as an increase in the frequency of replacement of spinning packs during spinning and an increase in the number of yarn breaks. PEP-36 or JP-318E is particularly preferable from the viewpoint of preventing a decrease in the amount of PEP-36 or JP-318E.

The type of phosphorus-based antioxidant contained in the copolymerized polyester composition obtained by the production method of the present invention can be identified by the following procedure. After dissolving about 1 g of the copolymerized polyester composition in 20 mL of HFIP, 40 mL of toluene is added. Then, 60 mL of methanol is added to precipitate. The prepared solution can be filtered through a 0.45 μm filter and the solvent removed from the filtrate using an evaporator to give an antioxidant. The obtained antioxidant is placed in an NMR measurement tube, and 1 g of deuterated HFIP is added and dissolved. By performing 1H-NMR measurement on this solution, the structure of the phosphorus-based antioxidant contained in the copolymerized polyester composition can be clarified and the type can be identified.

In the method for producing a copolymerized polyester of the present invention, a phosphorus-based antioxidant is added as a phosphorus content of 15.0 to 75.0 mmol / kg (0.10 to 0.25% by weight based on the weight of the copolymerized polyester). Is preferable. If the phosphorus content of the phosphorus-based antioxidant is less than 15.0 mmol / kg (0.10% by weight), yellowing will occur after the water washing treatment (JIS L0217-1995), and the heat resistance to oxidation will decrease. , Oxidation heat generation may occur in less than 90 hours. Further, when the phosphorus content of the phosphorus-based antioxidant is more than 75.0 mmol / kg (0.25% by weight), the orientation of the fibers made of the copolymerized polyester composition is suppressed, so that the fiber strength is lowered. , Frequent thread breakage in knitting and weaving processes, and deterioration of quality due to fluffing during use may occur. From the viewpoint of suppressing yellowing after washing with water, heat resistance to oxidation, and fiber strength, the phosphorus content of the phosphorus-based antioxidant is 35.0 to 65.0 mmol / kg (0.15 to 0.25% by weight). ) Is more preferable, and 35.0 to 50.0 mmol / kg (0.15 to 0.20% by weight) is particularly preferable.

The phosphorus content of the phosphorus-based antioxidant contained in the copolymerized polyester composition obtained by the production method of the present invention can be calculated by the following procedure. 10 mL of sulfuric acid is added to about 1 g of the copolymerized polyester, and the mixture is decomposed on a sand bath at 250 ° C. Add 1.0 mL of perchloric acid and further decompose at 300 ° C. When the sample becomes colorless and transparent, it is decomposed at 350 ° C. and refluxed with sulfuric acid. After cooling, neutralize with 20% aqueous sodium hydroxide solution. As the obtained solution and the sample solution, the absorbance at 720 nm can be measured with a spectrophotometer, and the phosphorus content can be calculated.

In the method for producing a copolymerized polyester of the present invention, the phosphorus-based antioxidant to be added is evaluated for weight loss by heating with a thermogravimetric differential thermal analyzer (TG-DTA) at a temperature rise rate of 10 ° C./min under a nitrogen atmosphere. When done, it is characterized in that the 5% weight loss temperature is 170 ° C. or higher. When the 5% weight loss temperature is less than 170 ° C., it decomposes and / or volatilizes during kneading and spinning, and the heat resistance to oxidation and the effect of suppressing yellowing of the obtained fiber tend to decrease. From the viewpoint of exhibiting heat resistance to oxidation and yellowing suppression effect, the 5% weight loss temperature is preferably 170 ° C. or higher, more preferably 180 ° C. or higher, further preferably 200 ° C. or higher, and particularly preferably 220 ° C. or higher.

In the method for producing a copolymerized polyester of the present invention, the phosphorus-based antioxidant to be added preferably has a molecular structure containing two or more phosphorus atoms in one molecule. When a phosphorus-based antioxidant having a molecular structure in which a phosphorus atom in one molecule is used is used, it volatilizes during kneading and spinning, and the heat-resistant oxidation resistance and the effect of suppressing yellowing of the obtained fiber are lowered. From the viewpoint of exhibiting heat resistance to oxidation and yellowing inhibitory effect, the phosphorus-based antioxidant preferably has a molecular structure containing two or more phosphorus atoms in one molecule.

The phosphorus-based antioxidant to be added in the method for producing a copolymerized polyester of the present invention has a melting point of 80 ° C. or higher. When the melting point of the phosphorus-based antioxidant is less than 80 ° C., it decomposes and / or volatilizes during kneading and spinning, and the heat resistance to oxidation and the effect of suppressing yellowing of the obtained fiber tend to decrease. From the viewpoint of exhibiting heat resistance to oxidation and yellowing suppression effect, the melting point is preferably 80 ° C. or higher, more preferably 100 ° C. or higher, further preferably 150 ° C. or higher, particularly preferably 180 ° C. or higher, and most preferably 200 ° C. or higher. preferable.

In the method for producing a copolymerized polyester of the present invention, the phosphorus-based antioxidant to be added preferably has a molecular structure represented by the following chemical formula (2), chemical formula (3) or chemical formula (4).

In the above formula (2), R represents a hydrocarbon group.

In the above formula (3), R represents a hydrocarbon group.

In the above formula (4), R represents a hydrocarbon group.

Examples of the phosphorus-based antioxidant having a molecular structure represented by the chemical formula (2) include HOSTANOX P-EPQ manufactured by Clariant Chemicals.

Examples of the phosphorus-based antioxidant having a molecular structure represented by the chemical formula (3) include ADEKA's ADEKA STAB (registered trademark) PEP-36.

Examples of the phosphorus-based antioxidant having a molecular structure represented by the chemical formula (4) include JP-318E manufactured by Johoku Chemicals.

Further, it is more preferable that the phosphorus-based antioxidant has a molecular structure represented by the chemical formulas (3) and / or (4). The inventors have stated that the phosphorus-based antioxidant reacts with the copolymerized polyester by transesterification to form foreign matter, which reduces the operability such as an increase in the frequency of replacement of the spinning pack during spinning and an increase in the number of yarn breaks. I found. Therefore, it is preferable that the phosphorus-based antioxidant to be added has a low transesterification reactivity. As a result of diligent studies by the inventor, the phosphorus-based antioxidant having the molecular structure represented by the chemical formulas (3) and / or (4) has a low transesterification reactivity with the copolymerized polyester and suppresses the formation of foreign substances. It was found that by doing so, it is possible to suppress an increase in the frequency of replacement of the spinning pack during spinning and a decrease in operability such as an increase in the number of yarn breaks. Therefore, it is preferable that the phosphorus-based antioxidant has a molecular structure represented by (3) and / or (4) from the viewpoint that the transesterification reactivity with the hydroxyl group is low and the formation of foreign matter after kneading can be suppressed. .. Further, when the number of carbon atoms contained in R in the molecular structure represented by (4) is less than 12, decomposition and / or volatilization occurs during kneading and spinning, and the resulting fiber has an oxidation heat resistance and heat resistance. The yellowing inhibitory effect tends to decrease. Therefore, from the viewpoint of exhibiting heat resistance to oxidation and yellowing inhibitory effect, the carbon number of R is preferably 12 or more, more preferably 15 or more, and particularly preferably 18 or more.

In the method for producing a copolymerized polyester of the present invention, the method for adding the above-mentioned phenolic antioxidant and phosphorus-based antioxidant to the copolymerized polyester is particularly limited in other conditions as long as the requirements specified in the present invention are satisfied. However, a method of uniformly melt-kneading the copolymerized polyester using a single-screw or twin-screw extruder as a kneader is preferable, and a twin-screw extruder can be used uniformly because fibers having excellent mechanical properties can be obtained. The method of kneading into is particularly preferable.

In the embodiment of the present invention, as a method of charging each component in the case of melt-kneading, for example, a copolymerized polyester composition is used from a main charging port installed on the screw root side using an extruder having two charging ports. A method of supplying a copolymerized polyester, a phenolic antioxidant, a phosphorus-based antioxidant and other components as necessary, which are the main components of the polyester composition, and the main component of the polyester composition, the copolymerized polyester and other components, from the main input port. A method of supplying a phenol-based antioxidant and a phosphorus-based antioxidant from a sub-feeding port installed between the main charging port and the tip of the extruder and melting and mixing them, and mechanical properties and production stability. A method of supplying a copolymerized polyester, a phenol-based antioxidant, a phosphorus-based antioxidant, and other components as necessary, which are the main components of the polyester composition, from the main inlet is preferable.

Particles may be added to the copolymerized polyester composition for the purpose of reducing friction with various guides in the molding process, contact objects such as rollers, improving process passability, and adjusting the color tone of the product. .. Any of the conventionally known particles can be used as the type of the particles. Specifically, for example, inorganic particles such as silicon dioxide, titanium dioxide, calcium carbonate, barium sulfate, aluminum oxide and zirconium oxide, and organic polymer particles such as crosslinked polystyrene can be used. Among these particles, titanium dioxide particles are preferable because they have good dispersibility in the polymer and are relatively low in cost. Titanium dioxide particles are produced by various wet and dry methods, and if necessary, are subjected to pretreatment such as pulverization and classification, and then added to the reaction system of the copolymerized polyester. The addition of the particles to the copolymerized polyester reaction system may be performed at any stage, but it is preferable to add the particles after substantially completing the esterification reaction or the transesterification reaction because the dispersibility in the polymer is improved. The amount of particles added to the polymer and the particle size vary depending on the application and are not particularly limited, but are 0.01 to 10% by weight based on the copolymerized polyester, the average particle size is 0.05 to 5 μm, and the particle size is 4 μm. When the number of the above coarse particles is in the range of 1000 particles / 0.4 mg or less, the process passability and the color tone are particularly good, which is preferable.

Further, after the polymerization, a blue-based adjusting agent, a red-based adjusting agent, and a purple-based adjusting agent may be added as the color tone adjusting agent. The color tone adjusting agent is as exemplified above, and one or a plurality of types can be used depending on the purpose. In particular, it is preferable to use one or more of each of the blue-based adjusting agent and the red-based adjusting agent because the color tone can be finely controlled. Further, in this case, when the ratio of the blue-based adjusting agent to the total amount of the color tone adjusting agent to be added is 50% by weight or more, the color tone of the obtained copolymerized polyester is particularly good, which is preferable. Finally, the total amount of the color tone adjusting agent added to the copolymerized polyester is preferably 30 ppm or less. If it exceeds 30 ppm, the transparency of the copolymerized polyester may decrease or the color may become dull. The amount added can be calculated from the structure specification of the color tone adjusting agent and the ratio of the constituent parts of the color tone adjusting agent by a nuclear magnetic resonance apparatus (NMR).

As other additives to be added after polymerization, in addition to the above-mentioned particles and color tone adjusters, pigments such as carbon black, surfactants such as alkylbenzene sulfonic acid, conventionally known antioxidants, anticoloring agents, and lightfastening agents. Antistatic agents, compatibilizers, plasticizers, fluorescent whitening agents, mold release agents, antibacterial agents, nucleating agents, modifiers, matting agents, defoaming agents, preservatives, gelling agents, latexs, fillers, inks , Colorants, fragrances and the like. These other additives may be used alone or in combination of two or more.

In the method for producing a polyester composition of the present invention, the melt-kneading temperature at the time of producing the polyester composition is preferably 110 to 360 ° C., more preferably 210 ° C. to 320 ° C., and 240 to 280 ° C. in terms of excellent mechanical properties. ° C is particularly preferred.

The copolymerized polyester composition obtained by the production method of the present invention preferably has an intrinsic viscosity (IV) of 1.50 dL / g or more, preferably 1.55 dL, when measured at 25 ° C. using o-chlorophenol as a solvent. / G or more is more preferable, 1.60 dL / g or more is further preferable, and 1.63 dL / g or more is particularly preferable. The upper limit is preferably 2.20 dL / g or less, more preferably 2.15 dL / g or less, and even more preferably 2.10 dL / g or less. Within this range, high-strength fibers with a high degree of polymerization can be obtained in the copolymerized polyester.

By using the copolymerized polyester composition obtained by the production method of the present invention as a constituent component of the composite fiber, it is possible to obtain a composite fiber that exhibits unprecedented hygroscopicity and does not impair the physical characteristics of the fiber.

Examples of specific embodiments of the composite fiber are described below.

Examples of the fiber form include core-sheath type composite fiber, core-sheath type composite hollow fiber, sea-island type composite fiber, and the polyester composition obtained by the production method of the present invention is used as a constituent component in an arbitrary ratio. Can be done. For example, in the case of a core-sheath type composite fiber and a core-sheath type composite hollow fiber, the composite ratio (% by weight) of the polyester composition in the core portion is preferably core / sheath = 10/90 to 90/10. It is more preferably 15/85 to 50/50, and particularly preferably 20/80 to 40/60. The lower limit of the composite ratio of the core portion is set for the purpose of imparting sufficient hygroscopicity, and the upper limit of the composite fiber ratio is set from the viewpoint of preventing deterioration of spinnability and fiber physical characteristics. In the case of the sea-island type composite fiber, the composite ratio (% by weight) of the polyester composition in the island portion is preferably island / sea = 10/90 to 90/10. It is more preferably 15/85 to 50/50, and particularly preferably 20/80 to 40/60. The lower limit of the composite ratio of the islands is set for the purpose of imparting sufficient hygroscopicity, and the upper limit of the composite fiber ratio is set from the viewpoint of preventing deterioration of spinnability and fiber physical properties.

As a method for producing a composite fiber using the copolymerized polyester composition obtained by the production method of the present invention and other polyesters, it can be produced by a conventional method, but the method for producing a sea-island type composite fiber is represented below. Is shown. In the case of a sea-island type composite fiber, the copolymerized polyester composition (island part) and polyester (sea part) obtained by the production method of the present invention are separately melted and guided to a spinning pack to generate a sea-island composite flow in a mouthpiece device. It is formed and spun from the discharge hole. After the spun filament yarn is taken up at a predetermined speed, it is once wound into a package, and the obtained undrawn yarn is drawn by a normal drawing machine. Further, the drawing may be performed continuously without winding after the spun yarn is taken up, or the yarn may be taken up at a high speed of 4000 m / min or more and the desired fiber performance may be obtained at once without substantially drawing. You may take the method of obtaining. Examples of the direct spinning and drawing method include a method in which the spun yarn is taken up at 1000 to 5000 m / min and then drawn and heat-fixed at 3000 to 6000 m / min. The filamentous form of the fiber may be either a filament or a staple, and is appropriately selected depending on the intended use. As the cloth form, a woven fabric, a knitted fabric, a non-woven fabric, or the like can be appropriately selected according to the purpose.

Hereinafter, the present invention will be described in more detail by way of examples. In addition, each characteristic value in an Example was obtained by the following method.

A. Extraction of Polyethylene Glycol in Copolymerized Polyester Extraction of polyethylene glycol in the copolymerized polyester was carried out by the following procedure, and the molecular weight of polyethylene glycol was measured by gel permeation chromatography (GPC).

The procedure for extracting polyethylene glycol in a copolymerized polyester is shown.

0.05 g of the obtained copolymerized polyester was collected, dissolved by heating in 1 mL of 28% ammonia water at 120 ° C. for 5 hours, allowed to cool, then 1 mL of purified water and 1.5 mL of 6M hydrochloric acid were added, and 5 mL of purified water was added. After constant volume and centrifugation, the mixture was filtered through a 0.45 μm filter, and the filtrate was used for GPC measurement.

B. Number Average Molecular Weight of Polyethylene Glycol The molecular weight of polyethylene glycol in the copolymerized polyester was analyzed by gel permeation chromatography (GPC) of the above-extracted filtrate.
Detector: Waters 2410 differential refractive index detector, sensitivity 128x
Column: Tosoh TSKgelG3000PWXLI
Solvent: 0.1M sodium chloride aqueous solution Flow rate: 0.8 mL / min
Injection volume: 200 μL
Column temperature: 40 ° C
Standard substance: Polyethylene glycol (Mw106-10100 manufactured by AML Co., Ltd.).

C. Copolymerization amount of polyethylene glycol The analysis of the copolymerization amount of polyethylene glycol in the copolymerized polyester was carried out using a nuclear magnetic resonance apparatus (NMR).
Equipment: AL-400 manufactured by JEOL Ltd.
Deuterated solvent: Deuterated 1,1,1,3,3,3-hexafluoro-2-isopropanol (HFIP)
Number of integrations: 128 times Sample concentration: 0.05 g of measurement sample / 1 mL of deuterated solvent.

D. Phosphorus atom content in polyethylene glycol or copolymerized polyester composition About 0.5 g of a sample is placed in a 100 mL Erlenmeyer flask, 10 mL of sulfuric acid is added, and the sample is heated to 250 ° C. on a sand bath. After adding 1 mL of perchloric acid, heat to 300 ° C., and further add 1 mL of perchloric acid. Heat at 350 ° C. for 10 minutes until the solution becomes colorless and transparent, and reflux the sulfuric acid for 3 minutes. After cooling, the treatment liquid is transferred to a 250 mL volumetric flask, titrated and neutralized with a 40% NaOH aqueous solution, and the volume is adjusted to 250 mL with pure water. To 10 mL of the obtained neutralizing solution, 2 mL of molybdenum blue coloring solution is added, and the volume is adjusted to 20 mL with pure water. After 15 minutes, the absorbance was measured at 720 nm with an absorptiometer. In advance, a calibration curve using the role for potassium dihydrogen phosphate was prepared, the amount of phosphoric acid in the sample was calculated, and the amount of phosphorus atom was further calculated.
Equipment: Hitachi High-Tech Science U-3310
Measurement wavelength: 720 nm.

E. Structural analysis of phosphorus compounds in polyethylene glycol Structural analysis of phosphorus compounds in polyethylene glycol was performed using the following equipment.
Equipment: Bruker FT-IR LUMOS
Light source: Silicon carbide rod heating element (Glover)
Detector: 250 μm Now ・ MCT
Detected wavenumber range: 4000-600 cm ^-1
Resolution: 4 cm ^-1
Accumulation number: 256 times or more.

F. Alkaline metal content in polyethylene glycol 0.1 g of polyethylene glycol is weighed in a container made of Teflon (registered trademark), sulfuric acid, nitric acid, hydrofluoric acid and perchloric acid are added, and the mixture is heat-decomposed on a hot plate and then sulfuric acid. It was concentrated until white smoke was generated and dissolved in dilute nitric acid to prepare a constant volume solution. The obtained constant volume liquid was measured for the metal content contained in polyethylene glycol using an ICP mass spectrometer (Asilent 8800 manufactured by Agent Tschologies), and the total amount of detected alkali metal atoms was calculated as the alkali metal in polyethylene glycol. Calculated as content
G. Extraction of Phenolic Antioxidant in Copolymerized Polyester or Copolymerized Polyester Composition Extraction of phenolic antioxidant in copolymerized polyester or copolymerized polyester composition is performed by the following procedure, and the structure of the phenolic antioxidant is performed. The analysis was performed using a nuclear magnetic resonance apparatus (NMR).

The procedure for extracting a phenolic antioxidant in a copolymerized polyester is shown.

About 1 g of the obtained copolymerized polyester or copolymerized polyester composition was dissolved in 20 mL of HFIP, and then 40 mL of toluene was added. Then, 60 mL of methanol was added and precipitated. The precipitate was removed with a 0.45 μm filter, and the filtrate was concentrated using an evaporator to obtain a dry product. This dry matter was used for 1H-NMR measurement or high performance liquid chromatogram (HPLC) measurement.

H. Structural analysis of the phenolic structural formula and the phenolic antioxidant in the copolymerized polyester or the copolymerized polyester composition The structural analysis of the phenolic structural formula and the phenolic antioxidant in the copolymerized polyester or the copolymerized polyester composition is carried out. It was carried out using a nuclear magnetic resonance apparatus (NMR).
Equipment: AL-400 manufactured by JEOL Ltd.
Deuterated solvent: Deuterated HFIP
Number of integrations: 128 times Sample concentration: 0.05 g of measurement sample / 1 mL of deuterated solvent.

I. Analysis of Polyester Group Content in Copolymerized Polyester or Copolymerized Polyester Composition Using the copolymerized polyester or fiber obtained in the example as a sample, 0.01 g of the sample was decomposed with 4 mL of 10% methanol hydrochloride at 80 ° C. After cooling, 1 mL of methanol hydrochloride was added and the precipitate was filtered. HPLC measurements were performed using the filtrate. Standard solutions are IRGANOX® 1010, 3- (3,5-di-tert-butyl-4-hydroxyphenyl) methyl propionate and 3- (3,5-di-tert-butyl-4-hydroxyphenyl). ) Propionic acid was prepared by dissolving each in a chloroform / acetonitrile solvent, a calibration line was prepared, and the phenol group content (mmol / kg) contained in the copolymerized polyester or fiber obtained by the examples was calculated. ..
Column: ODS-3 manufactured by Inertsil (3 x 150 mm, 5 μm)
Detector: LC-20A manufactured by Shimadzu Corporation
Mobile phase: A. 0.1 vol% aqueous solution of formic acid, B.I. Acetonitrile program: 0.0min → 10.0min B25% → 100%
10.0min → 20min B100%
Flow rate: 0.8 mL / min Injection volume: 20 μL
Column temperature: 50 ° C
Detection wavelength: PDA 260-280 nm.

J. Analysis of the content of the phenolic antioxidant in the copolymerized polyester or the copolymerized polyester composition The analysis of the content of the phenolic antioxidant in the copolymerized polyester or the copolymerized polyester composition is carried out using the precipitate according to Item G. HPLC measurements were performed using. The content of the phenolic antioxidant contained in the sample for HPLC measurement was quantified from the calibration curve of the standard substance (1,4-diphenylbenzene) prepared in advance. The measurement was performed 5 times per sample, and the average value was used.
Column: YMC-Pack ODS-A manufactured by YMC (inner diameter 4.6 mm, length 150 mm, particle diameter 5 nm) Detector: SPD-10AVVP manufactured by Shimadzu Corporation
Mobile phase: Methanol (solvent A), water (solvent B), solvent A: solvent B = 88:12
Flow rate: 1.3 mL / min Injection volume: 1 μL
Column temperature: 40 ° C
Standard substance: 1,4-diphenylbenzene.

K. Structural analysis of phosphorus-based antioxidants The structural analysis of phosphorus-based antioxidants contained in the copolymerized polyester composition using the precipitate obtained by the method described in Section G uses a nuclear magnetic resonance apparatus (NMR). It was carried out.
Equipment: AL-400 manufactured by JEOL Ltd.
Deuterated solvent: Deuterated HFIP
Number of integrations: 128 times Sample concentration: 0.05 g of measurement sample / 1 mL of heavy solvent.

L. In an environment of a fineness temperature of 20 ° C. and a humidity of 65% RH, 100 m of the fiber obtained in the examples was squeezed using an electric measuring machine manufactured by INTEC. The weight of the obtained skein was measured, and the fineness (dtex) was calculated using the following formula. The measurement was performed 5 times per sample, and the average value was taken as the fineness.

Fineness (dtex) = weight (g) of 100 m of fiber x 100.

M. Strength, Elongation The strength and elongation were calculated according to JIS L1013: 2010 (chemical fiber filament yarn test method) 8.5.1 using the fibers obtained in the examples as samples. A tensile test was carried out under the conditions of an initial sample length of 20 cm and a tensile speed of 20 cm / min using Tensilon UTM-III-100 manufactured by Orientec Co., Ltd. in an environment of a temperature of 20 ° C. and a humidity of 65% RH. The strength (cN / dtex) is calculated by dividing the stress (cN) at the point indicating the maximum load by the fineness (dtex), and the following is used using the elongation (L1) and the initial sample length (L0) at the point indicating the maximum load. The elongation (%) was calculated by the formula. The measurement was performed 10 times per sample, and the average value was taken as the intensity and elongation. When the intensity was 2.0 cN / dtex or more, it was judged to be good, and when it was 2.3 cN / dtex or more, it was further judged to be good.
Elongation (%) = {(L1-L0) / L0} × 100.

N. Difference in hygroscopicity of sample (△ MR)
(1) ΔMR of fabric
Using the obtained fiber as a sample, about 2 g of tubular knitting was prepared using a circular knitting machine NCR-BL (pot diameter 3.5 inches (8.9 cm), 27 gauge) manufactured by Eiko Sangyo, and then sodium carbonate 1 g / L. It was put into an aqueous solution containing the surfactant Granup US-20 manufactured by Meisei Chemical Works, and after scouring at 80 ° C. for 20 minutes, it was dried in a hot air dryer at 60 ° C. for 60 minutes to obtain a tube knitting after scouring. Further, the cylinder knitting after scouring is treated with hot water under the conditions of a bath ratio of 1: 100, a treatment temperature of 130 ° C., and a treatment time of 60 minutes, and then dried in a hot air dryer at 60 ° C. for 60 minutes. I knit it.

The moisture absorption rate (%) was calculated according to the moisture content of JIS L1096: 2010 (woven fabric and knitted fabric test method) 8.10 using the tube knitting after scouring and hot water treatment as a sample. First, the tube knitting is dried with hot air at 60 ° C. for 30 minutes, and then the tube knitting is allowed to stand in the Espec constant temperature and humidity chamber LHU-123 whose temperature is 20 ° C. and humidity is 65% RH for 24 hours. After measuring the weight of the knitting (W1), the tube knitting was allowed to stand for 24 hours in a constant temperature and humidity constant machine adjusted to a temperature of 30 ° C. and a humidity of 90% RH, and the weight of the tube knitting (W2) was measured. Then, the tube knitting was dried with hot air at 105 ° C. for 2 hours, and the weight (W3) of the tube knitting after absolute drying was measured. Using the weights W1 and W3 of the tube knitting, the hygroscopicity MR1 (%) when the product was allowed to stand in an RH atmosphere with a temperature of 20 ° C. and a humidity of 65% for 24 hours was calculated using the following formula, and the weight of the tube knitting was W2. After calculating the hygroscopicity MR2 (%) when the product is allowed to stand in a dry state at a temperature of 30 ° C. and a humidity of 90% RH for 24 hours using W3, the hygroscopicity difference (ΔMR) is calculated by the following formula. ) Was calculated. The measurement was performed 5 times per sample, and the average value was taken as the hygroscopicity difference (ΔMR). When ΔMR was 2.0% or more, it was judged to have hygroscopicity, and when it was 3.0% or more, it was considered to be even better.
MR1 (%) = {(W1-W3) / W3} x 100
MR2 (%) = {(W2-W3) / W3} x 100
Hygroscopicity difference (ΔMR) (%) = MR2-MR1.

(2) Chip ΔMR
3 g of the obtained chip was freeze-milled and used as a measurement sample. After drying with hot air at 60 ° C. for 30 minutes, the sample was allowed to stand in the Espec constant temperature and humidity chamber LHU-123 whose temperature was 20 ° C. and humidity was 65% RH for 24 hours, and the weight (W1) of the sample was measured. After that, the sample was allowed to stand for 24 hours in a constant temperature and humidity constant machine adjusted to a temperature of 30 ° C. and a humidity of 90% RH, and the weight (W2) of the tube knitting was measured. Then, the sample was dried with hot air at 105 ° C. for 2 hours, and the weight (W3) of the sample after absolute drying was measured. Using the sample weights W1 and W3, the hygroscopicity MR1 (%) when the sample was allowed to stand for 24 hours in an atmosphere of a temperature of 20 ° C. and a humidity of 65% RH was calculated by the above formula, and the sample weights W2 and W3 were calculated. After calculating the hygroscopicity rate MR2 (%) when the product is allowed to stand in a dry state at a temperature of 30 ° C. and a humidity of 90% RH for 24 hours using the above formula, the hygroscopicity difference (ΔMR) is calculated by the above formula. bottom.

O. Evaluation of yellowing suppression after washing with water The test was carried out in accordance with the 103 method of JIS L0217: 1995 (labeling symbols and labeling methods for handling textile products). After adding Kao Corporation's detergent "Attack" and 2.3 ml / L Kao Corporation's bleach "Highter" and repeating the washing process 10 times, dry it at 60 ° C for 30 minutes in a tumbler dryer. The cycle to be performed was set to one set, and this was repeated 10 sets. In the color tone measurement described later, as an evaluation of yellowing suppression after washing with water, "b * value is less than 10" is A, "b * value is 10 or more and 15 or less" is B, and "b * value is larger than 15". Was C.

P. Oxidation heat generation test (oxidation heat generation start time)
The samples prepared in O above and subjected to water washing treatment were stacked to a depth of 25 mm in a cylindrical container, and a thermocouple was installed in the center thereof. Further samples were stacked and filled in a cylindrical container without gaps. A cylindrical container filled with a sample was placed in a constant temperature dryer set at 150 ° C. for 200 hours, and the time at which oxidative heat generation started was measured. "No oxidative heat generation occurs even after 150 hours" is S, "No oxidative heat generation occurs even after 100 hours" is A, "Oxidation heat generation starts after 90 hours" is B, "Oxidation in less than 90 hours""Start of fever" was set as C, and S and A were set as pass.

Q. Nitrogen oxide fastness JIS L0855: 2005 (Staining fastness test method for nitrogen oxides) Weak test (1 cycle test) was performed. The tube knitting after scouring prepared in Item N (1) is used as a sample, exposed to nitrogen oxides, and post-treated with a buffered urea solution. Nitrogen oxide fastness was evaluated by classifying using a gray scale.

R. Spinning property evaluation (1) Pack replacement frequency As the spinnability, the pack replacement frequency when 92dtex-72f undrawn yarn is spun from the Kaishima composite mouthpiece using a filter with an opening of 5 μm using the polymer to be evaluated as an island component. evaluated. "Exchange period is 3 days or more" is S, "Exchange period is 1 day or more and less than 3 days" is A, "Exchange period is 12 hours or more and less than 24 hours" is B, and "Exchange period is less than 12 hours" is C. bottom.

(2) Number of yarn breaks The number of yarn breaks when an undrawn yarn of 92dtex-72f was spun from a Kaishima composite mouthpiece using a filter having an opening of 5 μm using a polymer to be evaluated as an island component as a spinnability was evaluated. "Number of thread breaks is 2 times / t or less" is S, "Number of thread breaks is 3 times / t or less" is A, "Number of thread breaks is 5 times / t or less" is B, "Number of thread breaks is 6 times / "T or more" was defined as C.

[Reference Example 1]
100 kg of bis (hydroxyethyl) terephthalate was charged in advance, and 82.5 kg of high-purity terephthalic acid (manufactured by Mitsui Kagaku Co., Ltd.) and 35.4 kg of ethylene glycol (manufactured by Nippon Catalyst Co., Ltd.) were charged in an esterification reaction tank maintained at a temperature of 250 ° C. The slurry was sequentially supplied over 4 hours, an esterification reaction was carried out for another 1 hour after the end of supply, and 101.5 kg of the obtained esterification reaction product was transferred to a polycondensation tank.

To this esterification reaction product, 25.3 g of trimethyl phosphate was added, and after 10 minutes, 20.3 g of cobalt acetate tetrahydrate and 25.3 g of antimony trioxide were added. After another 5 minutes, an ethylene glycol slurry of titanium oxide particles was added to the polymer in an amount of 0.3% by mass in terms of titanium oxide particles. After a further 5 minutes, the reaction system was depressurized and the reaction was started. The temperature inside the reactor was gradually raised from 250 ° C. to 290 ° C., and the pressure was lowered to 40 Pa. The time to reach the final temperature and final pressure was 60 minutes. When the predetermined stirring torque is reached, the reaction system is purged with nitrogen and returned to normal pressure to stop the polycondensation reaction, extruded into strands from the mouthpiece, cooled in a water tank, and cut to obtain polyethylene terephthalate (PET) pellets. rice field. The intrinsic viscosity of the obtained PET was 0.65.

(Example 1) Phosphorus amount: 27 ppm, alkali metal amount: 31.0 ppm (potassium amount: 1.0 ppm)
100 kg of bis (hydroxyethyl) terephthalate was charged in advance, and 51.9 kg of high-purity terephthalic acid (manufactured by Mitsui Kagaku Co., Ltd.) and 23.3 kg of ethylene glycol (manufactured by Nippon Catalyst Co., Ltd.) were charged in an esterification reaction tank maintained at a temperature of 250 ° C. The slurry was sequentially supplied over 4 hours, an esterification reaction was carried out for another 1 hour after the end of supply, and 60 kg of the obtained esterification reaction product was transferred to a polycondensation tank.

Number average molecular weight: 8300 g / mol, phosphorus content: 27 ppm, potassium content: 0.7 ppm, sodium content: 30.0 ppm, 60.0 kg of polyethylene glycol, antioxidant: pentaerythritol-tetrakis (3- (3) , 5-Di-t-butyl-4-hydroxyphenol) propionate) (BASF, IRGANOX (registered trademark) 1010) was put into a polymerization tank in an amount of 600 g, and when the temperature of the polymerization tank became 180 ° C. or higher, ES The reactants obtained in the reaction vessel were transferred.

30.0 g of trimethyl phosphate was added, and 10 minutes later, 20.4 g of cobalt acetate tetrahydrate and 48.0 of antimony trioxide were added. After another 5 minutes, an ethylene glycol slurry containing titanium oxide particles was added in an amount of 0.3% by mass in terms of titanium oxide particles with respect to the polymer. After a further 5 minutes, the reaction system was depressurized and the reaction was started. The temperature inside the reactor was gradually raised from 250 ° C. to 290 ° C., and the pressure was lowered to 40 Pa. The time to reach the final temperature and final pressure was 60 minutes. When the stirring torque reaches a predetermined value, the reaction system is purged with nitrogen and returned to normal pressure to stop the polycondensation reaction. Pellets were obtained. However, at the time of ejection, thickness was generated and the cutting property was poor.

(Example 2) Phosphorus amount: 40 ppm, alkali metal amount: 31.0 ppm (potassium amount: 1.0 ppm)
After heating 1.0 kg of butanediol (BDO) to 100 ° C., 250 g of titanium catalyst: tetra-n-butoxytitanate (TBT) (Tokyo Kasei) was mixed to obtain a catalyst solution.

Obtained by the above method as a dicarboxylic acid component terephthalic acid (TPA) (Tokyo Chemical Industry Co., Ltd.) 45.3 kg, as a diol component butanediol (BDO) (Tokyo Chemical Industry Co., Ltd.) 44.2 kg, as an esterification reaction catalyst. 135 g of the obtained catalyst solution was charged into an ES reaction tank equipped with a rectification column. After starting the esterification reaction under a reduced pressure of 160 ° C. and a pressure of 93 kPa, the temperature is gradually raised, and finally the esterification reaction is carried out under the condition of a temperature of 235 ° C. for 270 minutes. (500torr × 60 minutes) was carried out.

Number average molecular weight: 8300 g / mol, phosphorus content: 27 ppm, potassium content: 0.7 ppm, sodium content: 30.0 ppm, 60.0 kg of polyethylene glycol, antioxidant: pentaerythritol-tetrakis (3- (3) , 5-Di-t-butyl-4-hydroxyphenol) propionate) (BASF, IRGANOX (registered trademark) 1010) was put into a polymerization tank in an amount of 480 g, and when the temperature of the polymerization tank became 180 ° C. or higher, ES The reactants obtained in the reaction vessel were transferred. After the polymerization tank temperature reached 250 ° C., 300 g of the catalyst solution obtained by the above method was added as a polycondensation reaction catalyst, and the polycondensation reaction was carried out under the conditions of a temperature of 250 ° C. and a pressure of 100 Pa to obtain a predetermined stirring torque. At this point, the reaction system was purged with nitrogen and returned to normal pressure to stop the polycondensation reaction, extruded into strands from the base, cooled in a water tank, and cut to obtain pellets of polyethylene glycol copolymer polybutylene terephthalate. There was no problem with the polymerization discharge. The intrinsic viscosity of the obtained copolymerized polyester was 2.00.

Subsequently, with respect to the obtained polyethylene glycol copolymer polybutylene terephthalate, 2,2'-dimethyl-2,2'-(2,4,8,10-tetraoxaspiro [5,] as a phenolic antioxidant was used. 5] Undecane-3,9-diyl) Dipropane-1,1'diyl-bis [3- (3-t-butyl-4-hydroxy 5-methylphenyl) propanoart] (manufactured by ADEKA Co., Ltd., Adecastab (registered trademark) ) AO-80) in 6.0% by weight, as a phosphorus-based antioxidant 1,1'-biphenyl-4,4'-diylbis [bis phosphonate (2,4-di-t-butylphenyl)] ( HOSTANOX (registered trademark) P-EPQ manufactured by Clarianto Chemicals, containing 2.2% by weight, and having two or more vent holes with L / D = 45 (L represents the screw length and D represents the screw diameter). Using an extruder, the antioxidant was melt-kneaded under the conditions of a cylinder temperature of 250 ° C., a rotation speed of 200 rpm, and a discharge rate of 30 kg / h.

The obtained polyester composition is used as an island component, the polyester obtained in Reference Example 1 is used as a sea component, and each of them is dried to a moisture content of 300 ppm or less, and then the island component is 20% by mass and the sea component is 80% by mass. It is supplied to an extruder type composite spinning machine at the blending ratio of, melted separately, and flowed into a spinning pack (filter opening: 5 μm) incorporating a Kaishima composite mouthpiece at a spinning temperature of 285 ° C. A drawn yarn was obtained. Then, using a draw false twisting machine (twisting part: friction disc type, heater part: contact type), the obtained undrawn yarn was drawn and false twisted under the conditions of a heater temperature of 140 ° C. and a magnification of 1.4 times. A sea-island type composite false twist yarn of 66dtex-72f was obtained. There were no problems such as bleed-out in the drying preparation before spinning.

The polymer properties, fiber properties and fabric properties of the obtained copolymerized polyester are shown in Tables 1, 2 and 3. The fiber strength was 2.6 cN / dtex. At this time, the pack replacement frequency was "S" and the number of thread breaks was "B". The difference in hygroscopicity (ΔMR) after hot water treatment was 3.9%. The yellowing suppression after the water washing treatment was "A", and the oxidative heat generation after the water washing treatment was "S", which was good. The nitrogen oxide fastness test result was 4-5 grade.

(Example 3) Phosphorus amount: 20 ppm, alkali metal amount: 30.6 ppm (potassium amount: 0.6 ppm)
Example 2 except that polyethylene glycol having a number average molecular weight of 8300 g / mol, a phosphorus content of 20 ppm, a potassium content of 0.7 ppm, and a sodium content of 30.0 ppm was set to 60.0 kg in Example 2. It was carried out in the same manner as.

There was no problem with polymerization discharge, and the obtained fiber strength was 2.7 cN / dtex. The evaluation result of the pack replacement frequency at this time was "S", and the number of thread breaks was "A". The difference in hygroscopicity (ΔMR) after the hot water treatment was 4.0%. The yellowing suppression after the water washing treatment was "A", and the oxidative heat generation after the water washing treatment was "S", which was good. The nitrogen oxide fastness test result was 4-5 grade.

(Example 4) Phosphorus amount: 10 ppm, alkali metal amount: 30.4 ppm (potassium amount: 0.4 ppm)
Example 2 except that polyethylene glycol having a number average molecular weight of 8300 g / mol, a phosphorus content of 10 ppm, a potassium content of 0.4 ppm, and a sodium content of 30.0 ppm was set to 60.0 kg in Example 2. It was carried out in the same manner as.

There was no problem with polymerization discharge, and the obtained fiber strength was 2.7 cN / dtex. The evaluation result of the pack replacement frequency at this time was "S", and the number of thread breaks was "S". The difference in hygroscopicity (ΔMR) after the hot water treatment was 4.0%. The yellowing suppression after the water washing treatment was "A", and the oxidative heat generation after the water washing treatment was "S", which was good. The nitrogen oxide fastness test result was 4-5 grade.

(Example 5) Phosphorus amount: 0 ppm, alkali metal amount: 30.2 ppm (potassium amount: 0.2 ppm)
Example 2 and Example 2 except that the number average molecular weight: 8300 g / mol, phosphorus content: 0 ppm, potassium content: 0.2 ppm, sodium content: 30.0 ppm, polyethylene glycol 60.0 kg. It was carried out in the same manner.

There was no problem with polymerization discharge, and the obtained fiber strength was 2.6 cN / dtex. The evaluation result of the pack replacement frequency at this time was "S", and the number of thread breaks was "S". The difference in hygroscopicity (ΔMR) after the hot water treatment was 4.0%. The yellowing suppression after the water washing treatment was "A", and the oxidative heat generation after the water washing treatment was "S", which was good. The nitrogen oxide fastness test result was 4-5 grade.

(Example 6) Phosphorus amount: 0 ppm, alkali metal amount: 30.2 ppm (potassium amount: 0.2 ppm)
In Example 5, the phosphorus-based antioxidant added at the time of kneading was 3,9-bis (2,6-t-butyl-4-methylphenoxy) -2,4,8,10-tetraoxa-3,9-diphosphaspiro. It was carried out in the same manner as in Example 5 except that it was changed to [5,5 undecane] (made by ADEKA, ADEKA STAB (registered trademark) PEP-36) and the addition amount was changed to 1.4% by weight.

There was no problem with polymerization discharge, and the obtained fiber strength was 2.6 cN / dtex. The evaluation result of the pack replacement frequency at this time was "S", and the number of thread breaks was "S". The difference in hygroscopicity (ΔMR) after the hot water treatment was 4.0%. The yellowing suppression after the water washing treatment was "A", and the oxidative heat generation after the water washing treatment was "S", which was good. The nitrogen oxide fastness test result was 4-5 grade.

(Example 7) Phosphorus amount: 0 ppm, alkali metal amount: 35.0 ppm (potassium amount: 5.0 ppm)
Example 2 except that polyethylene glycol having a number average molecular weight: 8300 g / mol, phosphorus content: 0 ppm, potassium content: 5.0 ppm, and sodium content: 30.0 ppm was set to 60.0 kg in Example 2. It was carried out in the same manner as.

There was no problem with polymerization discharge, and the obtained fiber strength was 2.7 cN / dtex. The evaluation result of the pack replacement frequency at this time was "S", and the number of thread breaks was "S". The difference in hygroscopicity (ΔMR) after the hot water treatment was 4.0%. The yellowing suppression after the water washing treatment was "A", and the oxidative heat generation after the water washing treatment was "S", which was good. The nitrogen oxide fastness test result was 4-5 grade.

(Example 8) Phosphorus amount: 0 ppm, alkali metal amount: 45.0 ppm (potassium amount: 15.0 ppm)
Example 2 except that polyethylene glycol having a number average molecular weight of 8300 g / mol, a phosphorus content of 0 ppm, a potassium content of 15.0 ppm, and a sodium content of 30.0 ppm was set to 60.0 kg in Example 2. It was carried out in the same manner as.

There was no problem with polymerization discharge, and the obtained fiber strength was 2.7 cN / dtex. The evaluation result of the pack replacement frequency at this time was "A", and the number of thread breaks was "S". The difference in hygroscopicity (ΔMR) after the hot water treatment was 4.0%. The yellowing suppression after the water washing treatment was "A", and the oxidative heat generation after the water washing treatment was "S", which was good. The nitrogen oxide fastness test result was 4-5 grade.

(Example 9) Phosphorus amount: 0 ppm, alkali metal amount: 90.0 ppm (potassium amount: 60.0 ppm)
Same as Example 2 except that polyethylene glycol having a number average molecular weight: 8300 g / mol, phosphorus content: 0 ppm, potassium content: 60.0 ppm, and sodium content: 30 ppm was set to 60.0 kg in Example 2. It was carried out in.

There was no problem with polymerization discharge, and the obtained fiber strength was 2.7 cN / dtex. The evaluation result of the pack replacement frequency at this time was "B", and the number of thread breaks was "A". The difference in hygroscopicity (ΔMR) after the hot water treatment was 4.0%. The yellowing suppression after the water washing treatment was "A", and the oxidative heat generation after the water washing treatment was "S", which was good. The nitrogen oxide fastness test result was 4-5 grade.

(Example 10) Phosphorus amount: 0 ppm, alkali metal amount: 90.0 ppm (potassium amount: 0.2 ppm)
Example 2 except that polyethylene glycol having a number average molecular weight of 8300 g / mol, a phosphorus content of 0 ppm, a potassium content of 0.2 ppm, and a sodium content of 89.8 ppm was set to 60.0 kg in Example 2. It was carried out in the same manner as.

There was no problem with polymerization discharge, and the obtained fiber strength was 2.7 cN / dtex. The evaluation result of the pack replacement frequency at this time was "A", and the number of thread breaks was "A". The difference in hygroscopicity (ΔMR) after the hot water treatment was 4.0%. The yellowing suppression after the water washing treatment was "A", and the oxidative heat generation after the water washing treatment was "S", which was good. The nitrogen oxide fastness test result was 4-5 grade.

(Example 11) Amount of alkali metal: 150.0 ppm (amount of potassium: 120.0 ppm)
Example 2 except that polyethylene glycol having a number average molecular weight of 8300 g / mol, a phosphorus content of 0 ppm, a potassium content of 120.0 ppm, and a sodium content of 30.0 ppm was set to 60.0 kg in Example 2. It was carried out in the same manner as.

There was no problem with polymerization discharge, and the obtained fiber strength was 2.6 cN / dtex. The evaluation result of the pack replacement frequency at this time was "C", and the number of thread breaks was "B". The difference in hygroscopicity (ΔMR) after the hot water treatment was 4.0%. The yellowing suppression after the water washing treatment was "A", and the oxidative heat generation after the water washing treatment was "S", which was good. The nitrogen oxide fastness test result was 4-5 grade.

(Example 12) Alkali metal amount: 45.0 ppm (potassium amount: 15.0 ppm)
In Example 8, the phosphorus-based antioxidant added at the time of kneading was 3,9-bis (2,6-t-butyl-4-methylphenoxy) -2,4,8,10-tetraoxa-3,9-diphosphaspiro. It was carried out in the same manner as in Example 8 except that it was changed to [5,5 undecane] (made by ADEKA, ADEKA STAB (registered trademark) PEP-36) and the addition amount was changed to 1.4% by weight.

There was no problem with polymerization discharge, and the obtained fiber strength was 2.6 cN / dtex. The evaluation result of the pack replacement frequency at this time was "S", and the number of thread breaks was "S". The difference in hygroscopicity (ΔMR) after the hot water treatment was 4.0%. The yellowing suppression after the water washing treatment was "A", and the oxidative heat generation after the water washing treatment was "S", which was good. The nitrogen oxide fastness test result was 4-5 grade.

(Example 13) Alkali metal amount: 45.0 ppm (potassium amount: 15.0 ppm)
In Example 8, 1,1'-biphenyl-4,4'-diylbis [bisphosphorous acid (2,4-di-t-butylphenyl)] added at the time of kneading (manufactured by Clariant Chemicals, HOSTANOX®). The procedure was carried out in the same manner as in Example 8 except that the amount of P-EPQ) was 1.5% by mass.

There was no problem with polymerization discharge, and the obtained fiber strength was 2.6 cN / dtex. The evaluation result of the pack replacement frequency at this time was "S", and the number of thread breaks was "S". The difference in hygroscopicity (ΔMR) after the hot water treatment was 4.0%. The yellowing suppression after the water washing treatment was "A", and the oxidative heat generation after the water washing treatment was "S", which was good. The nitrogen oxide fastness test result was 4-5 grade.

(Example 14) Alkali metal amount: 45.0 ppm (potassium amount: 15.0 ppm)
In Example 12, 3,9-bis (2,6-t-butyl-4-methylphenoxy) -2,4,8,10-tetraoxa-3,9-diphosphaspiro [5,5 undecane] added at the time of kneading. The procedure was carried out in the same manner as in Example 12 except that the addition amount of (ADEKA, ADEKA STAB (registered trademark) PEP-36) was 0.9% by mass.

There was no problem with polymerization discharge, and the obtained fiber strength was 2.6 cN / dtex. The evaluation result of the pack replacement frequency at this time was "S", and the number of thread breaks was "S". The difference in hygroscopicity (ΔMR) after the hot water treatment was 4.0%. The yellowing suppression after the water washing treatment was "B", and the oxidative heat generation after the water washing treatment was "A", which was good. The nitrogen oxide fastness test result was grade 3-4.

(Example 15) Alkali metal amount: 45.0 ppm (potassium amount: 15.0 ppm)
In Example 8, the same procedure as in Example 8 was carried out except that the phosphorus-based antioxidant added at the time of kneading was tristearyl phosphite (manufactured by Johoku Chemical Co., Ltd., JP-318E) and the addition amount was 3.7% by mass. bottom.

There was no problem with polymerization discharge, and the obtained fiber strength was 2.7 cN / dtex. The evaluation result of the pack replacement frequency at this time was "S", and the number of thread breaks was "S". The difference in hygroscopicity (ΔMR) after the hot water treatment was 4.0%. The yellowing suppression after the water washing treatment was "A", and the oxidative heat generation after the water washing treatment was "S", which was good. The nitrogen oxide fastness test result was 4-5 grade.

(Example 16) Alkali metal amount: 150.0 ppm (potassium amount: 120.0 ppm)
Example 11 except that the phosphorus-based antioxidant added at the time of kneading was tristearyl phosphite (manufactured by Johoku Chemical Co., Ltd., JP-318E) and the addition amount was 3.7% by mass. It was carried out in the same manner as in 11.

There was no problem with polymerization discharge, and the obtained fiber strength was 2.7 cN / dtex. The evaluation result of the pack replacement frequency at this time was "B", and the number of thread breaks was "A". The difference in hygroscopicity (ΔMR) after the hot water treatment was 4.0%. The yellowing suppression after the water washing treatment was "A", and the oxidative heat generation after the water washing treatment was "S", which was good. The nitrogen oxide fastness test result was 4-5 grade.

(Example 17) Amount of alkali metal: 150.0 ppm (amount of potassium: 120.0 ppm)
In Example 16, the same procedure as in Example 16 was carried out except that the amount of tristearyl phosphite (manufactured by Johoku Chemical Co., Ltd., JP-318E) added at the time of kneading was 2.4% by mass.

There was no problem with polymerization discharge, and the obtained fiber strength was 2.6 cN / dtex. The evaluation result of the pack replacement frequency at this time was "A", and the number of thread breaks was "A". The difference in hygroscopicity (ΔMR) after the hot water treatment was 4.0%. The yellowing suppression after the water washing treatment was "A", and the oxidative heat generation after the water washing treatment was "S", which was good. The nitrogen oxide fastness test result was 4-5 grade.

(Example 18) Amount of alkali metal: 90.0 ppm (amount of potassium: 0.2 ppm)
In Example 10, the same procedure as in Example 10 was carried out except that the phosphorus-based antioxidant added at the time of kneading was tristearyl phosphite (manufactured by Johoku Chemical Co., Ltd., JP-318E) and the addition amount was 3.7% by mass. bottom.

There was no problem with polymerization discharge, and the obtained fiber strength was 2.7 cN / dtex. The evaluation result of the pack replacement frequency at this time was "A", and the number of thread breaks was "S". The difference in hygroscopicity (ΔMR) after the hot water treatment was 4.0%. The yellowing suppression after the water washing treatment was "A", and the oxidative heat generation after the water washing treatment was "S", which was good. The nitrogen oxide fastness test result was 4-5 grade.

(Example 19) Amount of alkali metal: 45.0 ppm (amount of potassium: 15.0 ppm)
Terephthalic acid (TPA) (Tokyo Chemical Industry Co., Ltd.) at the time of esterification reaction was 63.4 kg, butanediol (BDO) (Tokyo Chemical Industry Co., Ltd.) was 61.9 kg, and the esterification reaction catalyst solution was 189 g. Except for this, the esterification reaction was carried out in the same manner as in Example 2.

In the polycondensation reaction, the polyethylene glycol used was 36.0 kg of polyethylene glycol having a number average molecular weight of 8300 g / mol, a phosphorus content of 0 ppm, a potassium content of 15.0 ppm, and a sodium content of 30.0 ppm. It was carried out in the same manner as in Example 2. There was no problem with the polymerization discharge.

Kneading and spinning were carried out in the same manner as in Example 2, and the obtained fiber strength was 2.8 cN / dtex. The evaluation result of the pack replacement frequency at this time was "S", and the number of thread breaks was "S". The difference in hygroscopicity (ΔMR) after hot water treatment was 2.0%. The yellowing suppression after the water washing treatment was "A", and the oxidative heat generation after the water washing treatment was "S", which was good. The nitrogen oxide fastness test result was 4-5 grade.

(Example 20) Amount of alkali metal: 45.0 ppm (amount of potassium: 15.0 ppm)
In Example 19, the same procedure as in Example 19 was carried out except that the phosphorus-based antioxidant added at the time of kneading was tristearyl phosphite (manufactured by Johoku Chemical Co., Ltd., JP-318E) and the addition amount was 3.7% by mass. bottom.

There was no problem with polymerization discharge, and the obtained fiber strength was 2.8 cN / dtex. The evaluation result of the pack replacement frequency at this time was "S", and the number of thread breaks was "S". The difference in hygroscopicity (ΔMR) after hot water treatment was 2.0%. The yellowing suppression after the water washing treatment was "A", and the oxidative heat generation after the water washing treatment was "S", which was good. The nitrogen oxide fastness test result was 4-5 grade.

(Comparative Example 1)
In Example 2, the same procedure as in Example 2 was carried out except that the initial polymerization was not performed, PEG was not added at the time of polymerization, and the phenolic antioxidant and the phosphorus-based antioxidant were not added at the time of kneading.

There was no problem with polymerization discharge, and the obtained fiber strength was 3.0 cN / dtex. The evaluation result of the pack replacement frequency at this time was "S", and the number of thread breaks was "S". The difference in hygroscopicity (ΔMR) after the hot water treatment was 0.1%. The yellowing suppression after the water washing treatment was "A", and the oxidative heat generation after the water washing treatment was "S". The nitrogen oxide fastness test result was grade 5.

(Comparative Example 2)
In Example 2, the number average molecular weight: 8300 g / mol, phosphorus content: 40 ppm, potassium content: 1.0 ppm, sodium content: 30.0 ppm, 60.0 kg, antioxidant: pentaerythritol-tetrakis (3-). (3,5-di-t-butyl-4-hydroxyphenol) propionate) (manufactured by BASF, IRGANOX (registered trademark) 1010) 180 g was carried out in the same manner as in Example 2.

There was no problem with polymerization discharge, and the obtained fiber strength was 2.5 cN / dtex. The evaluation result of the pack replacement frequency at this time was "C", and the number of thread breaks was "C". The difference in hygroscopicity (ΔMR) after hot water treatment was 4.1%. The yellowing suppression after the water washing treatment was "A", and the oxidative heat generation after the water washing treatment was "S". The nitrogen oxide fastness test result was 4-5 grade.

Table 4 shows the chemical structural formulas of the phenolic compounds (phenolic antioxidants) and phosphorus-based antioxidants used in Examples and Comparative Examples.

The method for producing a polyester resin composition of the present invention can prevent a decrease in operability such as an increase in the frequency of replacement of a spinning pack during spinning and an increase in the number of yarn breaks, and has high hygroscopicity and after a water washing treatment. It is possible to provide a polyester composition capable of suppressing yellowing and suppressing heat generation of oxidation. Due to these characteristics, the polyester composition obtained in the present invention can be suitably used in applications requiring comfort and quality. Specific examples thereof include general clothing use, sports clothing use, bedding use, interior use, and material use.

Claims (5)

An esterification reaction or a transesterification reaction is carried out using an aromatic dicarboxylic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof, and the esterification reaction product obtained by the esterification reaction or the transesterification reaction is obtained. A method for producing a copolymerized ester in which a polyethylene glycol having a number average molecular weight of 5,000 to 20,000 is reacted in an amount of 10 to 50% by weight, and the amount of the phosphorus compound in the polyethylene glycol is less than 40 ppm as the phosphorus atom weight. A method for producing a copolymerized ester characterized by. The method for producing a copolymerized polyester according to claim 1, wherein an esterification reaction or a transesterification reaction is carried out using a diol containing 50 mol% or more of 1,4-butanediol or an ester-forming derivative thereof. The method for producing a copolymerized polyester according to claim 1 or 2, wherein the amount of the phosphorus compound in the polyethylene glycol is 30 ppm or less as the atomic weight of phosphorus. The method for producing a copolymerized polyester according to any one of claims 1 to 3, wherein the phosphorus atom in the polyethylene glycol is derived from phosphate. The method for producing a copolymerized polyester according to any one of claims 1 to 4, wherein the amount of the alkali metal compound in the polyethylene glycol is 100 ppm or less as the alkali metal atom weight.