JP2013249337A - Method for producing polyester composition for producing water absorptive polyester fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a polyester composition for producing a water absorptive polyester fiber having fine pores by a direct esterification method.SOLUTION: A method for producing a polyester composition, including a process of forming an oligomer from a dicarboxylic acid component consisting mainly of terephthalic acid and a diol component consisting mainly of ethylene glycol by an esterification reaction, and a process of performing a polycondensation reaction on the oligomer is characterized by adding a compound obtained by heat treating an alkali metal compound and/or an alkaline earth metal compound with a phosphorus compound having a specific chemical structure to the dicarboxylic acid component in a 0.1 to 2.0 mol% range of the incorporated alkali metal compound and/or alkaline earth metal compound in a process other than the process of forming the oligomer or the process of performing the polycondensation prior to production of the polyester composition, and also adding the phosphorus compound as satisfying a specific numeric formula.

Description

  The present invention relates to a method for producing a polyester composition for producing water-absorbing polyester fibers by a direct esterification method.

  Conventionally, at any stage of synthesizing and melt spinning a polyester composition, a specific metal phosphorus compound and / or metal sulfonic acid compound is added as a micropore forming agent, and after forming into a hollow fiber, an alkali weight loss treatment is performed. A method for producing a water-absorbing polyester fiber having fine pores has been proposed (see, for example, Patent Document 1).

  However, this method is very effective by adding the phosphorus compound and / or the sulfonic acid compound during the synthesis of the polyester composition by the so-called transesterification method using an organic carboxylic acid ester as an acid component, When the phosphorus compound and / or sulfonic acid compound is added during the synthesis of a polyester composition by a so-called direct esterification method using dicarboxylic acid as an acid component which has become the mainstream in recent years, the compound is coarse at the time of addition. Since the particles are formed, the polyester composition synthesized by the transesterification method has a problem that molding processability such as melt spinning is inferior and water absorption is inferior. Also, when the phosphorus compound and / or sulfonic acid compound is added at the stage of melt spinning, it is difficult to control the amount of precipitated fine particles and the particle size.

  As a method for suppressing the formation of coarse particles, a specific phosphorus compound and an alkali metal compound and / or an alkaline earth metal compound were individually added during synthesis of a polyester composition by a direct esterification method. There has been proposed a method of forming specific fine pores on the fiber surface by using a polyester composition as a fiber and performing an alkali weight loss treatment (see, for example, Patent Document 2). However, in this method, it does not become micropores that impart water absorption to the hollow fibers.

JP-A-57-011212 JP 2011-63646 A

  An object of the present invention is to produce a polyester composition for water-absorbing polyester fibers having fine pores by a direct esterification method.

  Means for solving the above-mentioned problems, that is, the present invention comprises a step of producing an oligomer by an esterification reaction from a dicarboxylic acid component mainly composed of terephthalic acid and a diol component mainly composed of ethylene glycol; In the method for producing a polyester composition having a step of performing a condensation reaction, an alkali metal compound and / or an alkaline earth metal compound in a step other than the step of producing an oligomer and the step of performing a polycondensation reaction before producing the polyester composition The compound obtained by heat-treating the phosphorus compound represented by the following general formula (I) is 0.1 to 2.0 alkali metal compound and / or alkaline earth metal compound relative to the dicarboxylic acid component. It is added so that it is contained in the range of mol%, and the phosphorus compound is added so as to satisfy the following formula (1). A process for producing a polyester composition, characterized by.

[In the above formula (I), Ar represents an unsubstituted or substituted aryl group having 6 to 20 carbon atoms, and R ¹ represents a hydrogen atom or an OR ² group. R ² is a hydrogen atom or an unsubstituted or substituted alkyl group having 1 to 20 carbon atoms, an unsubstituted or substituted aryl group having 6 to 20 carbon atoms, an unsubstituted or substituted 7 to Represents a benzyl group having 20 carbon atoms. ]
0.5 ≦ P / M ≦ 2.0 (1)
[In the above formula (1), P represents the molar amount of the phosphorus atom by the addition of the phosphorus compound, and M is the alkali metal atom and / or the alkaline earth metal atom by the addition of the alkali metal compound and / or alkaline earth metal compound. Represents molar amount. ]

  According to the present invention, a polyester composition is synthesized by a direct esterification method, which has become the mainstream in recent years, and after forming into a fiber, an alkali weight loss treatment is performed, thereby facilitating micropores that impart water absorption to the fiber surface. Therefore, the polyester composition can be a fiber having excellent water absorption compared to a polyester composition obtained by applying a known technique directly to the esterification method.

2 is a scanning electron micrograph of the polyester fiber surface obtained in Example 1. FIG. 2 is a scanning electron micrograph of the polyester fiber surface obtained in Example 2. FIG. 2 is a scanning electron micrograph of the surface of a polyester fiber obtained in Comparative Example 1. 2 is a scanning electron micrograph of the surface of a polyester fiber obtained in Comparative Example 2. 4 is a scanning electron micrograph of the surface of a polyester fiber obtained in Comparative Example 3.

  Hereinafter, the production method of the present invention will be described in detail. The method for producing a polyester composition of the present invention comprises a step of producing an oligomer by an esterification reaction from a dicarboxylic acid component mainly composed of terephthalic acid and a diol component mainly composed of ethylene glycol, and a polycondensation reaction is performed on the oligomer. It is a manufacturing method of the polyester composition which has a process.

(Raw material: Dicarboxylic acid component)
As the dicarboxylic acid component used in the present invention, terephthalic acid is mainly used, but other components may be copolymerized depending on the purpose within a range not losing physical properties. Components other than terephthalic acid include isophthalic acid, phthalic acid, phthalic anhydride, 5-sodium sulfoisophthalic acid, 5-tetrabutylphosphonium sulfoisophthalic acid, 4,4′-biphenyldicarboxylic acid, p-hydroxybenzoic acid, adipine Acid, sebacic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-cyclohexyldicarboxylic acid, etc. can be mentioned, but in order to maintain the basic quality of the resulting polyester composition It is preferable that 80 mol% or more, more preferably 90 mol% or more of the dicarboxylic acid component is terephthalic acid.

(Raw material: Diol component)
As the diol component used in the present invention, ethylene glycol is mainly used, but other components may be copolymerized depending on the purpose within a range not losing physical properties. As components other than ethylene glycol, 1,3-propanediol, 1,4-butanediol, diethylene glycol, 1,2-propylene glycol, 2,2-dimethyl-1,3-propanediol (neopentylene glycol), Examples include dipropylene glycol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dimethylolpropionic acid, poly (ethylene oxide) glycol, and poly (tetramethylene oxide) glycol. In order to maintain the basic quality of the obtained polyester composition, it is preferable that 80 mol% or more, more preferably 90 mol% or more of the diol component is ethylene glycol.

(Ingredients: other)
The polyester composition in the present invention is composed of a polycarboxylic acid such as trimellitic acid, trimesic acid, trimellitic anhydride, pyromellitic acid, trimellitic acid monopotassium salt, glycerin, pentaerythritol, sodium dimethylolethylsulfonate, A polyvalent hydroxy compound such as potassium methylolpropionate may be copolymerized within 1 mol% of the acid component as long as the object of the present invention is achieved.

(Oligomer)
In the manufacturing method of the polyester composition of this invention, the process of producing | generating an oligomer by esterification from the dicarboxylic acid component which mainly has terephthalic acid, and the diol component which mainly has ethylene glycol is included. Here, the oligomer means that the dicarboxylic acid component and the diol component are terephthalic acid and ethylene glycol, respectively, and in addition to bis (2-hydroxyethyl) terephthalate, the molecule contains two or more repeating units of ethylene terephthalate. Intrinsic viscosity, molecular weight, and degree of polymerization are not so high that it can be called terephthalate, and it represents a compound whose terminal is a carboxyl group or a hydroxyethyl group. The esterification reaction is performed until such an oligomer is formed. The reaction rate of the esterification reaction can be detected by measuring the amount of water produced.

(Intrinsic viscosity)
The polyester composition in the present invention preferably has an intrinsic viscosity of 0.60 dL / g or more. When the intrinsic viscosity is less than 0.60 dL / g, the physical properties of the fiber molded product obtained by melt spinning the polyester are lowered and the practicality is poor. The upper limit of the intrinsic viscosity is not particularly limited, but is preferably 1.2 dL / g or less from the viewpoint of ease of production of the polyester composition and ease of molding of a fiber molded article obtained therefrom. By appropriately adjusting the polycondensation conditions of the polyester, a polyester composition having an intrinsic viscosity within this range can be produced.

(Metallic phosphorus compound particles)
In the method for producing a polyester composition of the present invention, a step of producing an oligomer of a phosphorus compound represented by the following general formula (I) and an alkali metal compound and / or an alkaline earth metal compound before producing the polyester composition In addition, it is necessary to perform heat treatment in a process other than the process of performing the polycondensation reaction and use the resulting compound. Thus, it is characterized by adding the fine particle formed by making it heat-process in advance and making it react in processes other than these during the synthesis | combination of a polyester composition. By adding metal phosphorus compound particles formed by preheating and reacting in this way, the resulting polyester composition is formed into fibers and subjected to alkali weight loss treatment, and then water absorption is imparted to the fiber surface. Micropores can be formed. Here, “the process other than the process of generating the oligomer and the process of performing the polycondensation reaction” is a process included in the entire polyester composition manufacturing process, but other than the process of generating the oligomer and the process of performing the polycondensation reaction. Even if it is a process, it may be a separate and independent process that is not included in the entire polyester composition manufacturing process. Preferably, the heat treatment is performed in a separate and independent process that is not included in the entire polyester composition manufacturing process from the viewpoint of production efficiency and the like.

(Amount of metal phosphorus compound added)
It is necessary to add a metal phosphorus compound so that an alkali metal atom and / or an alkali metal atom may be contained in the range of 0.1 to 2.0 mol% in terms of metal atom, relative to the dicarboxylic acid component. When the addition amount is less than 0.1 mol%, the metal phosphorus compound particles formed from the phosphorus compound represented by the following general formula (I) and the alkali metal compound and / or the alkaline earth metal compound are reduced, and therefore, it is obtained. Formation of micropores on the surface of the polyester fiber obtained by melt spinning the polyester composition and then reducing the amount of alkali becomes insufficient, and sufficient water absorption cannot be expressed. On the other hand, if it exceeds 2.0 mol%, the spinning property is remarkably deteriorated in the step of melt spinning the resulting polyester composition, which is not preferable. The addition amount of these alkali metal compounds and / or alkaline earth metal compounds is preferably in the range of 0.2 to 1.8 mol%, more preferably in the range of 0.5 to 1.5 mol% in terms of metal atoms. .

(Metallic phosphorus compound addition time)
The timing of addition of the metal phosphorus compound during the production process of the polyester composition can be selected at any stage in the esterification reaction process and in the polycondensation reaction process, but from the influence on the esterification reaction and polycondensation reaction. It is desirable to add in the latter half of the esterification reaction or the first half of the polycondensation reaction (within 30 minutes from the start of the polycondensation reaction) after completion of the esterification reaction.

(Phosphorus compound)
The phosphorus compound in the present invention needs to be a compound represented by the following general formula (I).

[In the above formula (I), Ar represents an unsubstituted or substituted aryl group having 6 to 20 carbon atoms, and R ¹ represents a hydrogen atom or an OR ² group. R ² is a hydrogen atom or an unsubstituted or substituted alkyl group having 1 to 20 carbon atoms, an unsubstituted or substituted aryl group having 6 to 20 carbon atoms, an unsubstituted or substituted 7 to Represents a benzyl group having 20 carbon atoms. ]

When the functional group represented by R ² is an alkyl group, specifically, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl Group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, dodecyl group, tetradecyl group, hexadecyl group, octadecyl group, eicosyl group, phenyl group, naphthyl group, biphenyl group, benzyl group, methylphenyl group, ethylphenyl group Group, propylphenyl group, dimethylphenyl group and the like. Further, one or more hydrogen atoms in these hydrocarbon groups may be substituted with a carboxyl group, an ester group, a halogen group, an alkyloxy group or the like.

  Examples of the functional group represented by Ar include a phenyl group, a mono- (di- or tri-) halogenated phenyl group, a methoxyphenyl group, a mono- (di- or tri-) carboxyphenyl group, 1- ( 2-) naphthyl group, mono- (di- or tri-) halogenated-1- (2-) naphthyl group, 1- (2- or 9-) anthranyl group, 4- (2-, or , 3-) Biphenyl groups can be mentioned.

  Examples of the compound of the general formula (I) include phenylphosphonic acid, methylphosphonic acid, ethylphosphonic acid, normal propylphosphonic acid, isopropylphosphonic acid, butylphosphonic acid, tolylphosphonic acid, xylylphosphonic acid, biphenylphosphonic acid. Naphthylphosphonic acid, anthrylphosphonic acid, 2-carboxyphenylphosphonic acid, 3-carboxyphenylphosphonic acid, 4-carboxyphenylphosphonic acid, 2,3-dicarboxyphenylphosphonic acid, 2,4-dicarboxyphenylphosphonic acid 2,5-dicarboxyphenylphosphonic acid, 2,6-dicarboxyphenylphosphonic acid, 3,4-dicarboxyphenylphosphonic acid, 3,5-dicarboxyphenylphosphonic acid, 2,3,4-tricarboxyphenyl Phosphonic acid, 2, , 5-tricarboxyphenylphosphonic acid, 2,3,6-tricarboxyphenylphosphonic acid, 2,4,5-tricarboxyphenylphosphonic acid, 2,4,6-tricarboxyphenylphosphonic acid, Of these, phenylphosphonic acid is most preferably used.

  The phosphorus compound is desirably used in a state dissolved in a solvent. As a solvent at this time, an appropriate solvent can be selected from known solvents, but it is most preferable to use glycol which is a raw material of the target polyester composition.

(Alkali metals and alkaline earth metals)
The alkali metal atom and alkaline earth metal atom in the present invention are preferably Li, Na, Mg, Ca, Sr, Ba, and particularly preferably Ca, Sr, Ba. Of these, Ca is most preferably used. The alkali metal compound and / or alkaline earth metal compound in the present invention is not particularly limited as long as it reacts with the phosphorus compound represented by the general formula (I) to form a metal-containing phosphorus compound. Specifically, a salt with an organic carboxylic acid is preferable. Among them, acetate is particularly preferably used because acetic acid by-produced by the reaction can be easily removed. The above alkali metal compounds and / or alkaline earth metal compounds may be used alone or in combination of two or more.

  The alkali metal compound and / or alkaline earth metal compound is desirably used in a state dissolved in a solvent. As a solvent at this time, an appropriate solvent can be selected from known solvents, but it is most preferable to use glycol which is a raw material of the target polyester composition.

(Phosphorus atom / metal atom ratio)
The addition amount of the phosphorus compound, the alkali metal compound, and / or the alkaline earth metal compound needs to be added at a ratio represented by the following mathematical formula (1).
0.5 ≦ P / M ≦ 2.0 (1)
When the P / M in the above formula (1) is less than 0.5, the amount of the metal phosphorus compound particles decreases, and therefore the fine pores on the surface of the polyester fiber obtained by melt spinning the resulting polyester composition and then reducing the alkali amount are obtained. Formation is insufficient, sufficient water absorption cannot be expressed, the amount of the alkali metal compound and / or alkaline earth metal compound in the polyester composition is excessive, and the excessive metal atom component promotes thermal decomposition of the polyester, This is not preferable because the thermal stability is remarkably impaired. On the other hand, when P / M exceeds 2.0, the phosphorus compound becomes excessive, and the excessive phosphorus compound inhibits the polymerization reaction of the polyester, which is not preferable. P / M is preferably in the range of 0.8 to 1.8, more preferably 0.9 to 1.5.

(Method for preparing metal phosphorus compound particles)
By mixing a phosphorus compound dissolved in a solvent with an alkali metal compound and / or an alkaline earth metal compound so as to satisfy the above mathematical formula (1) and performing a heat treatment, a slurry liquid of metal phosphorus compound particles can be obtained. . As described above, the heat treatment step is preferably a separate and independent step that is not included in the entire polyester composition manufacturing step. The temperature of the heat treatment is preferably in the range of 40 to 150 ° C. More preferably, the heat treatment temperature is 60 to 130 ° C. As a solvent at this time, an appropriate solvent can be selected from known solvents, but it is most preferable to use glycol which is a raw material of the target polyester composition.

(Polymerization catalyst, other additives)
The polyester composition of the present invention includes a metal compound catalyst for compounds such as antimony, germanium, and titanium, which are usually used in the production of polyester, a phosphorus compound as an anti-coloring agent, an antioxidant, an optical brightener, and an antistatic agent. An agent, an antibacterial agent, an ultraviolet absorber, a light stabilizer, a heat stabilizer, a light-shielding agent, a matting agent, or the like may be contained within a range that achieves the object of the present invention.

(Production method of polyester composition)
Next, an example of the preferable manufacturing method for obtaining the polyester composition of this invention is demonstrated in detail. That is, after the polyester is formed, the metal phosphorus compound is mixed by a method such as blending to obtain a polyester composition, but the polyester is subjected to a polymerization reaction of the polyester by adding the metal phosphorus compound during the polyester production process. A method for producing a composition. Further, the polyester production conditions in the present invention are not particularly limited, but the polycondensation reaction is generally performed at a temperature of 230 to 320 ° C. under normal pressure or reduced pressure (0.1 Pa to 0.1 MPa), or these It is preferable to carry out polycondensation for 15 to 300 minutes by combining these conditions.

(Melt spinning, alkali weight loss)
A conventional polyester fiber melt spinning method can be arbitrarily adopted as a method of melt spinning and fiberizing the polyester composition obtained by the above method. The fiber to be spun here is preferably a hollow fiber having a hollow portion, and the through micropores from the fiber surface to the hollow portion impart water absorption to the hollow portion by capillary action.
As a method of forming fine pores that impart water absorption to the surface of the polyester fiber thus obtained, a method of reducing the amount by contacting with a basic compound is preferable. The contact with the basic compound can be easily performed by, for example, treating the fiber with an aqueous solution of the basic compound after subjecting the fiber to a treatment such as stretching heat treatment or false twisting as necessary, or further forming a fabric. It can be carried out.

Examples of the basic compound used here include sodium hydroxide, potassium hydroxide, tetramethylammonium hydroxide, sodium carbonate, potassium carbonate and the like. Of these, sodium hydroxide and potassium hydroxide are particularly preferred. The concentration of the basic compound aqueous solution varies depending on the type of the basic compound, processing conditions, and the like, but is particularly preferably in the range of 0.1 to 30% by weight. The treatment temperature is preferably in the range of room temperature to 100 ° C.
The amount by which the polyester fiber is reduced by the treatment of this basic compound aqueous solution or the like is preferably 2% by weight or more, preferably 5% by weight or more, more preferably 10% by weight or more based on the fiber weight.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not restrict | limited to these Examples. In addition, the analysis item etc. in an Example were measured by the method of the following description.
(A) Intrinsic viscosity:
A dilute solution obtained by dissolving the polyester composition in orthochlorophenol at 100 ° C. for 60 minutes was determined from a value measured at 35 ° C. using an Ubbelohde viscometer.
(A) Diethylene glycol content:
The polyester sample chip was decomposed using hydrazine hydrate (hydrated hydrazine), and the content of diethylene glycol in the decomposition product was measured using gas chromatography (manufactured by Hewlett-Packard (HP 6850)).
(C) Fiber surface structure:
The fabric after the alkali weight reduction was observed at 5000 times with a scanning electron microscope.
(D) Phosphorus atom and metal atom content in the polyester composition:
A test molded body having a flat surface with a compression press machine after heating and melting a granular polyester composition (fiber) sample on a steel plate with a phosphorus atom content, a sulfur atom content, and a metal atom content in the polyester composition It was created. It calculated | required using the fluorescent X ray apparatus (Rigaku Co., Ltd. ZSX100e) using this test molded object.

[Example 1]
5.7 parts of phenylphosphonic acid and 6.3 parts of calcium acetate are charged into 88 parts of ethylene glycol charged in a reaction tank equipped with a stirrer installed separately from the esterification reaction tank and the polycondensation reaction tank. Then, heat treatment was performed at 70 ° C. for 120 minutes to obtain a phenylphosphonic acid calcium salt slurry. In this slurry liquid, P / M in the formula (1) was 1.0.
In an esterification reaction tank, 65 parts of terephthalic acid and 35 parts of ethylene glycol were subjected to an esterification reaction according to a conventional method to obtain an oligomer. To this oligomer, 65 parts of terephthalic acid and 35 parts of ethylene glycol were continuously supplied over 135 minutes, and an esterification reaction was performed at 250 ° C. Then, 0.053 parts of antimony trioxide was added and 30 minutes later, an oligomer having an equimolar amount equal to the amount of oligomer produced from the additionally supplied terephthalic acid and ethylene glycol was fed to the polycondensation reaction tank. Immediately after completion of the liquid feeding, 12 parts of the previously prepared slurry of phenylphosphonic acid calcium salt was added to the polycondensation reaction tank. The addition ratio of calcium atoms to terephthalic acid was 1.0 mol% in terms of metal atoms. Thereafter, the temperature was raised to 285 ° C., and a polycondensation reaction was performed at a high vacuum of 0.03 kPa or less to obtain a polyester chip having an intrinsic viscosity of 0.64 dL / g.
This chip was dried at 160 ° C. for 4 hours, and melt-spun at 280 ° C. using a spinneret having a hole diameter of 0.27 mm (circular) and 24 holes. The obtained undrawn yarn was drawn 4.16 times to obtain a drawn yarn of 82.6 dtex / 24 filament.
The obtained drawn yarn is knitted, and then the obtained knitted fabric is subjected to scouring and presetting according to a conventional method, and then treated at a boiling temperature in a sodium hydroxide aqueous solution having a concentration of 1% by weight. A 19.1% by weight fabric was obtained. The weight-reduced fabric was observed with an electron microscope. The results are shown in Table 1.

[Example 2]
In Example 1, ethylene glycol charged with 5.7 parts of phenylphosphonic acid and 6.3 parts of calcium acetate in a reaction vessel equipped with a stirrer installed separately from the esterification reaction vessel and the polycondensation reaction vessel The mixture was put into 88 parts and heat-treated at 120 ° C. for 120 minutes to obtain a phenylphosphonic acid calcium salt slurry. In this slurry liquid, P / M in the formula (1) was 1.0. The esterification reaction and polycondensation reaction were carried out in the same manner as in Example 1 to obtain a polyester chip having an intrinsic viscosity of 0.66 dL / g. The addition ratio of calcium atoms to terephthalic acid was 1.0 mol% in terms of metal atoms.
This chip was melt-spun in the same manner as in Example 1, and the obtained undrawn yarn was drawn 3.73 times to obtain a drawn yarn of 89.5 dtex / 24 filament. Thereafter, an alkali weight loss treatment was performed in the same manner as in Example 1 to obtain a fabric having a weight loss rate of 19.4% by weight. The weight-reduced fabric was observed with an electron microscope. The results are shown in Table 1.

[Comparative Example 1: A known technique is directly applied to an esterification method (described in Patent Document 1)]
3.7 parts of 5-sodium sulfoisophthalic acid and 2.9 parts of magnesium acetate tetrahydrate were charged into a reaction vessel equipped with a stirrer installed separately from the esterification reaction vessel and the polycondensation reaction vessel. Into 93 parts of ethylene glycol, heat treatment was performed at 70 ° C. for 120 minutes to obtain a transparent solution of 5-sodium sulfoisophthalic acid magnesium salt. In this transparent solution, when the molar amount of sulfur atoms is represented by S and the molar amount of alkaline earth metal atoms, that is, magnesium atoms, is represented by M, S / M was 1.0. P / M in the formula (1) was 0.
In an esterification reaction tank, 65 parts of terephthalic acid and 35 parts of ethylene glycol were subjected to an esterification reaction according to a conventional method to obtain an oligomer. To this oligomer, 65 parts of terephthalic acid and 35 parts of ethylene glycol were continuously supplied over 135 minutes, and an esterification reaction was performed at 250 ° C. Then, after maintaining the temperature for 30 minutes, an oligomer having an equimolar amount equal to the amount of oligomer produced from the additionally supplied terephthalic acid and ethylene glycol was fed to the polycondensation reaction tank. Immediately after completion of the liquid feeding, 0.00013 part of trimellitic acid titanium was added to the polycondensation reaction tank, and 14 parts of the previously prepared transparent solution of 5-sodium sulfoisophthalic acid magnesium salt was added to the polycondensation reaction tank. The addition ratio of magnesium atoms to terephthalic acid was 0.50 mol% in terms of metal atoms. Thereafter, the temperature was raised to 285 ° C., and a polycondensation reaction was performed at a high vacuum of 0.03 kPa or less to obtain a polyester chip having an intrinsic viscosity of 0.67 dL / g.
This chip was melt-spun in the same manner as in Example 1, and the obtained undrawn yarn was drawn 4.20 times to obtain a drawn yarn of 83.9 dtex / 24 filament. Thereafter, an alkali weight loss treatment was performed in the same manner as in Example 1 to obtain a fabric having a weight loss rate of 19.5% by weight. The weight-reduced fabric was observed with an electron microscope. The results are shown in Table 1.

[Comparative Example 2]
1.9 parts of 5-sodium sulfoisophthalic acid and 1.5 parts of magnesium acetate tetrahydrate are charged into a reaction vessel equipped with a stirrer installed separately from the esterification reaction vessel and the polycondensation reaction vessel. In the same manner as in Comparative Example 1, a transparent solution of 5-sodium sulfoisophthalic acid magnesium salt was obtained. In this clear solution, S / M was 1.0. P / M in the formula (1) was 0.
The esterification reaction and polycondensation reaction were carried out in the same manner as in Comparative Example 1 until the addition of titanium trimellitic acid. Thereafter, 28 parts of the previously prepared transparent solution of 5-sodium sulfoisophthalic acid magnesium salt was added to the polycondensation reaction tank, and a polycondensation reaction was carried out in the same manner as in Comparative Example 1 to obtain a polyester having an intrinsic viscosity of 0.67 dL / g. I got a chip. The addition ratio of magnesium atoms to terephthalic acid was 0.50 mol% in terms of metal atoms.
This chip was melt-spun in the same manner as in Example 1, and the obtained undrawn yarn was drawn 4.31 times to obtain a drawn yarn of 78.5 dtex / 24 filament. Thereafter, an alkali weight loss treatment was performed in the same manner as in Example 1 to obtain a fabric having a weight loss rate of 23.2% by weight. The weight-reduced fabric was observed with an electron microscope. The results are shown in Table 1.

[Comparative Example 3]
0.96 parts of 5-sodium sulfoisophthalic acid and 0.77 parts of magnesium acetate tetrahydrate were charged into a reaction vessel equipped with a stirrer installed separately from the esterification reaction vessel and the polycondensation reaction vessel. In the same manner as in Comparative Example 1, a transparent solution of 5-sodium sulfoisophthalic acid magnesium salt was obtained. In this clear solution, S / M was 1.0. P / M in the formula (1) was 0.
The esterification reaction and polycondensation reaction were carried out in the same manner as in Comparative Example 1 until the addition of titanium trimellitic acid. Thereafter, 56 parts of the previously prepared transparent solution of 5-sodium sulfoisophthalic acid magnesium salt was added to the polycondensation reaction tank, and a polycondensation reaction was carried out in the same manner as in Comparative Example 1 to obtain a polyester having an intrinsic viscosity of 0.65 dL / g. I got a chip. The addition ratio of magnesium atoms to terephthalic acid was 0.50 mol% in terms of metal atoms.
This chip was melt-spun in the same manner as in Example 1, and the obtained undrawn yarn was drawn 4.43 times to obtain a drawn yarn of 77.2 dtex / 24 filament. Thereafter, an alkali weight loss treatment was performed in the same manner as in Example 1 to obtain a fabric having a weight loss rate of 20.4% by weight. The weight-reduced fabric was observed with an electron microscope. The results are shown in Table 1.

  The polyester fiber obtained from the polyester composition obtained in the Examples of the present application has many fine pores on the fiber surface by the alkali weight reduction treatment, and exhibits excellent water absorption. However, the polyester fiber obtained by the comparative example has a small number of fine pores on the fiber surface even when the same treatment is performed, and coarse pores are generated, so that it cannot exhibit water absorption.

  According to the present invention, a polyester composition is synthesized by a direct esterification method, which has become the mainstream in recent years, and after forming into a fiber, an alkali weight loss treatment is performed, thereby facilitating micropores that impart water absorption to the fiber surface. Therefore, the polyester composition can be a fiber having excellent water absorption compared to a polyester composition obtained by applying a known technique directly to the esterification method. The industrial significance of such effects is significant.

Claims (2)

In a process for producing a polyester composition comprising a step of producing an oligomer by an esterification reaction from a dicarboxylic acid component mainly composed of terephthalic acid and a diol component mainly composed of ethylene glycol, and a step of performing a polycondensation reaction on the oligomer An alkali metal compound and / or an alkaline earth metal compound and a phosphorus compound represented by the following general formula (I) in a step other than the step of generating an oligomer and the step of performing a polycondensation reaction before the production of the polyester composition The compound obtained by the heat treatment is added so that the alkali metal compound and / or alkaline earth metal compound is contained in the range of 0.1 to 2.0 mol% with respect to the dicarboxylic acid component, and phosphorus is added. A method for producing a polyester composition, wherein the compound is added so as to satisfy the following formula (1): .
[In the above formula (I), Ar represents an unsubstituted or substituted aryl group having 6 to 20 carbon atoms, and R ¹ represents a hydrogen atom or an OR ² group. R ² is a hydrogen atom or an unsubstituted or substituted alkyl group having 1 to 20 carbon atoms, an unsubstituted or substituted aryl group having 6 to 20 carbon atoms, an unsubstituted or substituted 7 to Represents a benzyl group having 20 carbon atoms. ]
0.5 ≦ P / M ≦ 2.0 (1)
[In the above formula (1), P represents the molar amount of the phosphorus atom by the addition of the phosphorus compound, and M is the alkali metal atom and / or the alkaline earth metal atom by the addition of the alkali metal compound and / or alkaline earth metal compound. Represents molar amount. ]   The manufacturing method of the polyester composition of Claim 1 whose heat processing temperature of the alkali metal compound and / or alkaline-earth metal compound, and the phosphorus compound represented by the said general formula (I) is the range of 40-150 degreeC. .