JP4649199B2 - Polyester composition and polyester fiber comprising the same - Google Patents

Description

  The present invention has excellent antistatic properties and excellent dyeability at a pressure of from normal pressure to 110 ° C., and is excellent in sharpness and deep color dyeability, and has good yarn-making properties even when spinning by a high-speed spinning method. The present invention relates to a polyester composition capable of obtaining a fine fiber, a method for producing the same, and a polyester fiber excellent in dyeability and antistatic properties at a pressure of from normal pressure to 110 ° C.

  Polyester fiber fabrics, particularly polyalkylene terephthalates such as polyethylene terephthalate and polybutylene terephthalate and polyester fiber fabrics mainly composed of these are excellent in terms of mechanical strength, durability, functionality, etc., and are widely used. Therefore, there is a drawback in that various troubles are likely to occur during manufacturing, processing, and use. Conventionally, various methods for solving such drawbacks have been proposed.

  On the other hand, polyester fiber fabrics are difficult to be dyed, and general dyeing conditions are performed at a high temperature of about 130 ° C. For this reason, there is a problem that it is difficult to dye a mixed fiber fabric with other material yarns. There is no polyester yet that has both sufficient antistatic properties for the current diversifying material demands and dyeability capable of mixing with other materials.

  As a method for imparting antistatic properties to polyester, for example, the simplest method includes a method of applying an antistatic agent to the fiber surface. In this case, the antistatic agent is easily lost by a dyeing process or washing, There is a drawback that a permanent anti-electric effect cannot be expected. The durability of the antistatic effect in the antistatic fiber fabric is a basic required characteristic. In order to obtain this characteristic, a method of modifying the polyester itself by kneading an antistatic agent into the polymer, for example, polyoxyalkylene glycol Has been proposed (see, for example, Patent Document 1). However, since a very large amount of polyoxyalkylene glycol is required to exhibit sufficient antistatic properties by this method, the mechanical properties and light resistance of the obtained antistatic polyester fibers are greatly reduced and cannot be used. It will be a thing.

  Further, in the above method, the dyeability at a temperature of 110 ° C. or less is insufficient, and a polyester having both the dyeability and the antistatic property has not been obtained yet. In particular, according to the study by the present inventors, when the dye is exhausted at a temperature of 110 ° C. or less, the hue has a dull feeling and it is difficult to obtain a sufficient hue.

Thus, many methods such as coating method, kneading method, and composite spinning method have been proposed as an antistatic method, but a practical level of antistatic effect, its durability, mechanical properties, light resistance, The present condition is that the thing which simultaneously satisfies atmospheric pressure dyeing | staining property in about 110 degreeC, deep color dyeing | staining property, vividness, manufacturing cost, etc. is not obtained. Furthermore, in high-speed spinning methods, it is common to perform polymer filtration at higher temperatures and stricter conditions than normal spinning methods, and easy dyeing and antistatic properties that satisfy thermal degradation, pressure increase and yarn-forming properties in the yarn-making process. Fabrics using polyester fibers have not yet been obtained.
Japanese Examined Patent Publication No. 39-5214 Patent Claim

  The object of the present invention is to solve the above-mentioned problems of the prior art, have excellent antistatic properties, easy dyeability, thermal stability at the time of melting, good spinning properties even when spinning by a high-speed spinning method, To provide a polyester composition having good deep colorability and sharpness even in dyeing under normal pressure to pressure of 110 ° C., and having excellent antistatic property, easy dyeability, and thermal stability. To provide fiber.

  As a result of intensive studies in view of the above problems, the present inventors have a good antistatic effect without impairing the excellent properties unique to polyester fibers, and are excellent in atmospheric pressure dyeability around 110 ° C. The present inventors have found that a polyester having a deep color and sharpness and capable of suppressing process failures even in high-speed spinning can be easily obtained.

That is, the present invention is a polyester composition comprising a copolymerized polyester in which polyethylene glycol, which is a polyoxyalkylene glycol having a weight average molecular weight of 400 or more and less than 4500, is copolymerized at a ratio of 1% by mass or more and 8% by mass or less,
(A) For the copolymer polyester,
(A) 0.03 mass% or more and 1 mass% or less of titanium dioxide,
(B) 0.1-10 mass ppm of organic color adjuster,
(C) 5 to 50 ppm by mass of monomethyl terephthalate,
(D) 0.5% by mass or more and 5% by mass or less of an alkali metal sulfonate, and
(E) Polyoxyalkylene glycol having a weight average molecular weight of 8000 or more
Contain,
(B) The average particle size of the titanium dioxide is 0.1 μm or more and 0.5 μm or less, and the mass fraction of particles having a particle size exceeding 1 μm is 0.5% by mass or more and 2% by mass or less, and Li, Na, Containing at least one element selected from the group of K and Al in the titanium dioxide from 0.01% by mass to 0.5% by mass,
(C) The composition of the organic color adjusting agent includes a blue color adjusting dye and a purple color adjusting dye in a mass ratio of 90:10 to 40:60, and the concentration of the organic color adjusting agent is 20 mg. When the visible light absorption spectrum in the wavelength range of 380 to 780 nm was measured for a chloroform solution of / L at an optical path length of 1 cm, the maximum absorption wavelength was in the range of 540 to 600 nm, and the absorbance at the maximum absorption wavelength was as follows. Polyester composition in which the ratio of absorbance satisfies all of the following mathematical formulas (1) to (4) 0.00 ≦ A ₄₀₀ / A _max ≦ 0.20 (1)
0.10 ≦ A ₅₀₀ / A _max ≦ 0.70 (2)
0.55 ≦ A ₆₀₀ / A _max ≦ 1.00 (3)
0.00 ≦ A ₇₀₀ / A _max ≦ 0.05 (4)
[In the above formula, A ₄₀₀ , A ₅₀₀ , A ₆₀₀ and A ₇₀₀ each have a wavelength of 400 nm,
The absorbance in the visible light absorption spectrum at 500 nm, 600 nm and 700 nm is expressed as A
_max represents the absorbance in the visible light absorption spectrum at the maximum absorption wavelength. ]
It is.

  Excellent antistatic properties, dyeability at normal pressure to 110 ° C, little deterioration of physical properties due to thermal deterioration, and good spinning performance without using complicated spinning technology even when spinning by high-speed spinning method It is possible to provide a polyester composition capable of obtaining a simple fiber.

  Hereinafter, the present invention will be described in detail. The copolymerized polyester used in the present invention is a copolymerized polyester obtained by copolymerizing a polyoxyalkylene glycol having a weight average molecular weight of 400 or more and less than 4500 to 1% by mass or more and 8% by mass or less with respect to the copolymerized polyester.

  As the polyester used in the present invention, a polyester mainly composed of an ethylene terephthalate unit obtained by a polycondensation reaction of terephthalic acid and ethylene glycol is preferably used. Here, “main” means that 70 mol% or more of all repeating units are ethylene terephthalate units. Preferably it is 80 mol% or more. However, the present invention is not limited to this. For example, as a dicarboxylic acid component other than the terephthalic acid component, an acid component such as isophthalic acid, adipic acid, sebacic acid, naphthalenedicarboxylic acid or the like may be used. As other glycol components, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol and the like may be used. Among these, polyethylene terephthalate is more preferable.

  The polyester in the present invention needs to be copolymerized with a polyoxyalkylene glycol having a weight average molecular weight of 400 or more and less than 4500. The polyoxyalkylene glycol may be either a homo form or a copolymer. Preferable examples include polyethylene glycol, polypropylene glycol, copolymers thereof, and the like, and these may be used as a single species or a plurality of species may be used simultaneously. Of these, polyethylene glycol is preferred.

  The weight average molecular weight of the polyoxyalkylene glycol needs to be 400 or more and less than 4500. When the weight average molecular weight is less than 400, a large amount of copolymerization is required to obtain dyeability at normal pressure to a pressure below 110 ° C., and as a result, physical properties such as the strength and elongation of the resulting fiber are significantly lost. Therefore, it is not preferable. On the other hand, when the weight average molecular weight is 4500 or more, the glass transition temperature (Tg) of the copolyester is not sufficiently lowered, and as a result, the dyeability at a pressure below normal pressure to 110 ° C. is deteriorated. The preferable range of the weight average molecular weight is 600 to 4000, more preferably 1000 to 4000, and further preferably 1500 or more and 4000.

  The copolymerization amount of polyoxyalkylene glycol for obtaining sufficient dyeability needs to be 1% by mass or more and 8% by mass or less. If it is less than 1% by mass, the effect of improving the dyeability is poor, and if it exceeds 8% by mass, the physical properties of the resulting fiber are lowered or the durability and antistatic properties are inferior. A preferable range of the copolymerization amount is 2% by mass or more and 7% by mass or less, and a particularly preferable range is 3% by mass or more and 6% by mass or less.

  The polyester composition of this invention needs to contain 0.03 mass% or more and 1 mass% or less of titanium dioxide with respect to copolyester. If it is less than 0.03 mass%, the gloss of the polyester becomes shining and the quality of the product is impaired. Even if it exceeds 1% by mass, the matte feeling is no longer improved, but rather it may adversely affect the process condition such as an increase in pack pressure and yarn breakage. Furthermore, the average particle diameter of titanium dioxide needs to be 0.1 μm or more and 0.5 μm or less, the mass fraction of particles having a particle diameter exceeding 1 μm is 0.5 mass% or more and 2 mass% or less, and Li, Na It is necessary to contain 0.01% by mass or more and 0.5% by mass or less of at least one element selected from the group of K, Al. If the average particle size is less than 0.1 μm, the specific surface area of the particles is too large, and it becomes easy to form aggregated particles when producing the polyester composition, which is not preferable. On the other hand, if the average particle size exceeds 0.5 μm, it is not preferable because an increase in pack pressure and yarn breakage during spinning increase. Furthermore, if the mass fraction of the particles having a particle size exceeding 1 μm exceeds 2% by mass, for example, when forming a polyester composition, it may cause yarn breakage, thermal degradation will increase, and coloring during melting may occur. This causes a problem in moldability at the time of molding such as remarkable, and when the alkali is reduced after spinning, the fine pores formed on the fiber surface become large and the color developability at the time of dyeing is lowered, which is not preferable. On the other hand, the lower limit of the proportion of particles exceeding 1 μm is preferable, but it is difficult to produce such titanium dioxide particles with few coarse particles and the cost increases. It is preferable to set it as the mass% or more. There are various methods for adjusting the average particle size of such titanium dioxide and the mass fraction of particles having a particle size exceeding 1 μm. For example, there is a method in which a slurry in which titanium dioxide is dispersed in a dispersion medium is once prepared and then supplied to a sand grinder together with a crushing medium and pulverized as necessary. Specifically, it is possible to finely adjust the slurry flow rate, the pulverization time / number of times, the presence / absence / type of the crushing medium, and further filtering by a filter having a predetermined mesh size after pulverization.

  The titanium dioxide in the present invention further contains at least one element selected from the group of Li, Na, K and Al, in an amount of 0.01% by mass to 0.5% by mass based on the total mass of the titanium dioxide particles. It is necessary to contain. These elements may be single or plural. When the content of these elements is less than 0.01% by mass, the melt stability of the polyester composition is lowered, which is not preferable. On the other hand, when it exceeds 0.5% by mass, the hue of the polyester composition is lowered, which is not preferable. More preferably, it is the range of 0.03-0.3 mass%, and the range of 0.04-0.15 mass% is still more preferable. The content of Li, Na, K, and Al in such titanium dioxide is adjusted by, for example, the following method. That is, in order to increase the content, a method using an ore having a high content of these elements as the original ore in the production process of titanium dioxide, or an element containing Li, Na, K, or Al as an organic acid in the firing process. This can be achieved by the method of adding the compound. On the other hand, to reduce the content, it can be achieved by a method using an ore with a low content or a method of removing together with foreign matters or washing water in a hydrolysis step when producing titanium dioxide.

  There is no particular limitation on the method of blending such titanium dioxide into the polyester. For example, it may be blended before the start of the polyester polycondensation reaction, during the polycondensation reaction, at the end of the polycondensation reaction, etc. After manufacturing polyester by this, you may mix this pellet and titanium dioxide with an extruder.

The polyester composition of this invention needs to contain 0.1-10 mass ppm of organic color adjusting agents on the basis of the total mass of copolyester. The organic color adjusting agent represents an organic polyaromatic ring dye or pigment. Specific examples thereof include a blue color adjusting dye, a purple color adjusting dye, a red color adjusting dye, and an orange color adjusting dye as described later. These may be used alone or in combination of two or more. It is preferable to use a plurality of types in combination in terms of easily satisfying the requirements regarding the visible light absorption spectrum as described later. Furthermore, the organic color adjusting agent has a maximum absorption wavelength in the range of 540 to 600 nm when the visible light absorption spectrum in the wavelength range of 380 to 780 nm is measured for a chloroform solution with a concentration of 20 mg / L at an optical path length of 1 cm, and the maximum The ratio of the absorbance at each wavelength below to the absorbance at the absorption wavelength must satisfy all of the following mathematical formulas (1) to (4).
0.00 ≦ A ₄₀₀ / A _max ≦ 0.20 (1)
0.10 ≦ A ₅₀₀ / A _max ≦ 0.70 (2)
0.55 ≦ A ₆₀₀ / A _max ≦ 1.00 (3)
0.00 ≦ A ₇₀₀ / A _max ≦ 0.05 (4)
[In the above formula, A ₄₀₀ , A ₅₀₀ , A ₆₀₀ and A ₇₀₀ are the absorbance in the visible light absorption spectrum at wavelengths of 400 nm, 500 nm, 600 nm and 700 nm, respectively, and A _max is the absorbance in the visible light absorption spectrum at the maximum absorption wavelength. Represents. ]

  Here, the visible light absorption spectrum is a spectrum usually measured by a spectrophotometer, but the maximum absorption wavelength of the visible light absorption spectrum of the organic colorant solution contained in the polyester composition of the present invention is less than 540 nm. In such a case, the redness of the resulting polyester composition becomes strong, and when it exceeds 600 nm, the blueness of the resulting polyester composition becomes strong, which is not preferable. The range of the maximum absorption wavelength is preferably 545 to 595 nm, and more preferably 550 to 590 nm.

Moreover, when the visible light absorption spectrum was measured at an optical path length of 1 cm for a chloroform solution having a concentration of 20 mg / L of the organic color adjusting agent contained in the polyester composition of the present invention, at each wavelength shown above with respect to the absorbance at the maximum absorption wavelength. When the ratio of the absorbance of any one of the above formulas (1) to (4) deviates, the resulting polyester composition is unfavorably colored. It is more preferable to satisfy the above formulas (1) to (4), and more preferably to satisfy any one or more of the following formulas (5) to (8), and further satisfy all the following formulas (5) to (8). More preferably.
0.00 ≦ A ₄₀₀ / A _max ≦ 0.15 (5)
0.30 ≦ A ₅₀₀ / A _max ≦ 0.60 (6)
0.60 ≦ A ₆₀₀ / A _max ≦ 0.95 (7)
0.00 ≦ A ₇₀₀ / A _max ≦ 0.03 (8)
[In the above formula, A ₄₀₀ , A ₅₀₀ , A ₆₀₀ and A ₇₀₀ are the absorbance in the visible light absorption spectrum at wavelengths of 400 nm, 500 nm, 600 nm and 700 nm, respectively, and A _max is the absorbance in the visible light absorption spectrum at the maximum absorption wavelength. Represents. ]

  Furthermore, when content of the above-mentioned organic color adjusting agent contained in the polyester composition of the present invention is less than 0.1 mass ppm, the yellowness of the polyester composition becomes strong. On the other hand, if it exceeds 10 ppm by mass, the brightness becomes weak and the blackness becomes strong visually, which is not preferable. The content of the organic color adjusting agent is preferably in the range of 0.3 mass ppm to 9 mass ppm, and more preferably in the range of 0.5 to 8 mass ppm.

The organic color adjusting agent used in the present invention is selected from color adjusting dyes having a mass decrease starting temperature of 250 ° C. or higher when measured with a thermobalance in a nitrogen atmosphere at a temperature rising rate of 10 ° C./min. It is preferable that Here, the mass decrease start temperature when measured with a thermobalance is the mass decrease start temperature (T ₁ ) described in JIS K-7120, and is an index of heat resistance possessed by the organic color matching agent. It becomes. When the mass decrease starting temperature is less than 250 ° C., the heat resistance of the organic color adjusting agent is insufficient, which is not preferable because it causes coloring of the finally obtained polyester composition. The mass decrease starting temperature is more preferably 300 ° C. or higher. More preferably, the copolyester does not decompose at a temperature at which it is in a molten state.

  In the polyester composition of the present invention, a blue color adjusting dye and a purple color adjusting dye are used in combination in a mass ratio of 90:10 to 40:60 as an organic color adjusting agent, or for blue color adjusting. It is preferable to use the dye and the red or orange color adjusting dye in a mass ratio of 98: 2 to 80:20. Here, the blue color-modifying dye is generally indicated as “Blue” among commercially available color-adjusting dyes, and specifically, the maximum absorption in the visible light absorption spectrum in the solution. The wavelength is about 580 to 620 nm. Similarly, the purple color-modifying dye is the one described as “Violet” among commercially available color-adjusting dyes, and specifically has a maximum absorption wavelength in a visible light absorption spectrum in a solution. The thing in about 560-580 nm is shown. The red color-modifying dyes are those listed as “Red” among commercially available color-adjusting dyes. Specifically, the maximum absorption wavelength in the visible light absorption spectrum in the solution is 480 to 480. It is about 520 nm. The orange-based color-adjusting colorant is the one described as “Orange” among commercially available color-adjusting colorants.

  As these color adjusting pigments, oil-soluble dyes are particularly preferable. Specific examples of blue color adjusting pigments include C.I. I. Solvent Blue 11, C.I. I. Solvent Blue 25, C.I. I. Solvent Blue 35, C.I. I. Solvent Blue 36, C.I. I. Solvent Blue 45 (Telasol Blue RLS), C.I. I. Solvent Blue 55, C.I. I. Solvent Blue 63, C.I. I. Solvent Blue 78, C.I. I. Solvent Blue 83, C.I. I. Solvent Blue 87, C.I. I. Solvent Blue 94 and the like. Examples of purple color adjusting pigments include C.I. I. Solvent Violet 8, C.I. I. Solvent Violet 13, C.I. I. Solvent Violet 14, C.I. I. Solvent Violet 21, C.I. I. Solvent Violet 27, C.I. I. Solvent Violet 28, C.I. I. Solvent Violet 36 etc. are mentioned. Examples of red color adjusting pigments include C.I. I. Solvent Red 24, C.I. I. Solvent Red 25, C.I. I. Solvent Red 27, C.I. I. Solvent Red 30, C.I. I. Solvent Red 49, C.I. I. Solvent Red 52, C.I. I. Solvent Red 100, C.I. I. Solvent Red 109, C.I. I. Solvent Red 111, C.I. I. Solvent Red 121, C.I. I. Solvent Red 135, C.I. I. Solvent Red 168, C.I. I. Solvent Red 179 etc. are illustrated. Examples of the orange color adjusting dye include C.I. I. Solvent Orange 60 etc. are mentioned.

Here, when the blue color adjusting dye and the purple color adjusting dye are used in combination, when the mass ratio of the blue color adjusting dye is larger than the mass ratio 90:10, the color a ^* value of the obtained polyester composition Is small and exhibits a green color, and when the mass ratio of the blue color adjusting pigment is smaller than 40:60, the color a ^* value increases and a red color is exhibited, which is not preferable. Similarly, in the case where a blue color adjusting dye and a red or orange color adjusting dye are used in combination, when the mass ratio of the blue color adjusting dye is larger than 98: 2, the color of the resulting polyester composition If the a ^* value is small and green, and the mass ratio of the blue color-changing dye is smaller than 80:20, the color a ^* value becomes large and red is not preferable. The color adjusting dye is a combination of a blue color adjusting dye and a purple color adjusting dye in a mass ratio of 80:20 to 50:50, or a blue color adjusting dye and a red or orange color. It is more preferable to use the color adjusting dye in a mass ratio of 95: 5 to 90:10.

  The polyester composition in this invention needs to contain 5-50 mass ppm of monomethyl terephthalate (MMT) with respect to copolyester. When monomethyl terephthalate is present in an amount in this range, the orientation of the amorphous part is disturbed particularly in high-speed spinning, and the effect of improving the exhaustion rate of the dye, visual deep color, and sharpness is achieved. If the content of monomethyl terephthalate is less than 5 ppm by mass, the effect of disturbing the structure of the amorphous part is poor, which is not preferable. If the content of monomethyl terephthalate exceeds 50 ppm by mass, the polymerization reaction rate decreases and the amount of foreign matter on the die surface during spinning is increased. This is not preferable because it causes deterioration of the process condition. The monomethyl terephthalate content can be achieved by using terephthalic acid or dimethyl terephthalate having a high MMT content as a raw material, or adding MMT into the reactor during the polymerization reaction. When MMT is added during the polymerization reaction, it can be added at any stage. The content can be reduced by using terephthalic acid or dimethyl terephthalate purified to a high purity. Moreover, in order to obtain highly purified terephthalic acid or dimethyl terephthalate, it can be achieved by increasing the reaction rate in the previous reaction step or paying sufficient attention to the purification conditions in the purification step such as distillation. .

  The polyester composition in the present invention may further contain a known copolymer, a known antistatic agent, a known antioxidant and the like. Examples of known antistatic agents include alkali metal sulfonates and polyoxyalkylene glycols having a weight average molecular weight of 8000 or more.

Among these, when using a sulfonic acid alkali metal salt, it is preferable to contain 0.5 mass% or more and 5 mass% or less of sulfonic acid alkali metal salt with respect to copolyester. Examples of the sulfonic acid alkali metal salt include alkyl sulfonic acid alkali metal salts and alkylbenzene sulfonic acid alkali metal salts. The alkylsulfonic acid alkali metal salt is a compound represented by the general formula R—SO ₃ M (wherein R is an alkyl group having 8 to 20 carbon atoms, M is a metal atom of Li, Na, or K). Specific examples include sodium octyl sulfonate, sodium dodecyl sulfonate, sodium tetradecyl sulfonate, sodium stearyl sulfonate, and the like. On the other hand, the alkali metal salt of alkylbenzene sulfonic acid has the following general formula (III)

［上記式中のＲ’は炭素数８〜２０のアルキル基、Ｍ’はＬｉ、Ｎａ又はＫの金属原子を表す。］
で表される化合物であり、具体的にはオクチルベンゼンスルホン酸ナトリウム、ドデシルベンゼンスルホン酸ナトリウム、テトラデシルベンゼンスルホン酸ナトリウム等が挙げられる。これらを単一種で用いても、複数種を同時に用いても良い。

[R ′ in the above formula represents an alkyl group having 8 to 20 carbon atoms, and M ′ represents a metal atom of Li, Na or K. ]
Specific examples include sodium octylbenzenesulfonate, sodium dodecylbenzenesulfonate, sodium tetradecylbenzenesulfonate, and the like. These may be used as a single species or a plurality of species may be used simultaneously.

  According to the study by the present inventors, among them, an alkylsulfonic acid alkali metal salt is preferably used in that the conductive phase is satisfactorily formed in the polyester matrix. The alkyl chain length is preferably 8 to 20 carbon atoms. If the number of carbon atoms is less than 7, the compatibility with the polyester is poor, and sublimable foreign matter may be generated during spinning, or the fiber surface may bleed out. On the other hand, when the carbon number exceeds 20, the antistatic performance becomes inferior. Examples of the metal salt include Li, Na, K, and the like. Na is more preferable because it has excellent antistatic properties and hardly generates aggregated foreign matters. That is, the sulfonic acid alkali metal salt is more preferably an alkylsulfonic acid sodium salt. The content of these alkali metal sulfonates is also preferably 0.5% by mass or more and 5% by mass or less. If the amount is less than 0.5% by mass, the antistatic performance is poor, and if it exceeds 5% by mass, the physical properties of the fiber become inferior. A preferable range of the content of the alkali metal sulfonate is 0.7% by mass or more and 4% by mass or less.

  On the other hand, when polyoxyalkylene glycol having a weight average molecular weight of 8000 or more is used as an antistatic agent, the weight average molecular weight of polyoxyalkylene glycol is more preferably in the range of 10,000 to 25,000. Polyoxyalkylene glycol in the same range does not copolymerize with polyester and is in a microphase-separated state with polyester in the fiber, and is considered to function as a charge transfer carrier, but if the molecular weight is 10,000 or less, polyester Microscopically, the compatibilization proceeds, the antistatic effect is poor, and if it exceeds 25,000, the heat resistance becomes poor. Furthermore, it is preferable to use an antioxidant effectively in order to improve durability.

  The above components, that is, alkali metal alkyl sulfonate, alkali metal alkyl benzene sulfonate, polyoxyalkylene glycol having a weight average molecular weight of 600 or more and less than 4500, polyoxyalkylene glycol having a weight average molecular weight of 8000 or more, etc. (hereinafter referred to as “alkyl sulfonic acid”) There is no particular limitation on the method for blending the copolymerized polyester of the present invention into the copolymerized polyester of the present invention, and any stage until the formation of the copolymerized polyester, for example, the start of the polycondensation reaction of the copolymerized polyester is started. It may be blended before, during the polycondensation reaction, at the end of the polycondensation reaction, etc., and after the polyester composition is produced by a normal method, the composition pellets and the alkali metal salt of alkyl sulfonic acid are extruded with an extruder. You may mix. Alkyl sulfonic acid alkali metal salts and the like may be blended simultaneously or separately. Among these methods, from the viewpoint of copolymerization, it is preferable from the viewpoint of dispersibility that polyoxyalkylene glycol is blended simultaneously with these additives before the start of polyester polycondensation reaction or during the polycondensation reaction.

  Furthermore, when the polyester composition in the present invention uses a catalyst containing a titanium compound or an aluminum compound as its polycondensation catalyst, it can improve the yarn-making property, and further dye it at a pressure under normal pressure to 110 ° C. When performed, the deep color and sharpness are further improved, which is preferable.

  Here, the titanium compound is not particularly limited, and examples thereof include a general titanium compound as a polyester polycondensation catalyst, such as titanium acetate and tetra-n-butoxy titanium. More preferable as the titanium compound is a titanium compound represented by the following general formula (I), a titanium compound represented by the following general formula (I) and an aromatic polyvalent carboxylic acid represented by the following general formula (II) or A product obtained by reacting with an anhydride or a titanium compound represented by the following general formula (IV) is used.

[上記式中、Ｒ_１、Ｒ_２、Ｒ_３及びＲ_４はそれぞれ互いに独立に、炭素数１〜１０のアルキル基又はフェニル基を示し、ｍは１〜４の整数を示し、かつｍが２、３又は４の場合、２個、３個又は４個のＲ_２及びＲ_３は、互いに異なっていてもよい。]

[In the above formula, R ₁ , R ₂ , R ₃ and R ₄ each independently represent an alkyl group having 1 to 10 carbon atoms or a phenyl group, m represents an integer of 1 to 4, and m is 2 In the case of 3 or 4, 2, 3 or 4 R ₂ and R ₃ may be different from each other. ]

［上記式中、ｑは２〜４の整数を表わす。］

[In the above formula, q represents an integer of 2 to 4. ]

［上記式中、Ｘは炭素数１〜２０のアルキル基、アルコキシ基、又は炭素数６〜２０のアリール基、アリールオキシ基である。］

[In the above formula, X represents an alkyl group having 1 to 20 carbon atoms, an alkoxy group, or an aryl group or aryloxy group having 6 to 20 carbon atoms. ]

  On the other hand, the aluminum compound is not particularly limited, but is preferably an organoaluminum compound from the viewpoint of catalytic activity. Among them, aluminum acetylacetonate is preferable because it is stable and easy to handle. In addition, these titanium compounds and aluminum compounds may be used either individually or in combination, or two or more of each compound may be used together, but the titanium compound is used alone. Is particularly preferred. Of these, the compound represented by the above general formula (I) or the compound represented by the above general formula (I) and the aromatic polyvalent carboxylic acid represented by the above general formula (II) or an anhydride thereof is most preferable. The reacted product is used alone.

Among the titanium compounds represented by the general formula (I), tetraalkoxide titanium and / or tetraphenoxide titanium are particularly limited as long as R _{1 to} R ₄ are alkyl groups or phenyl groups having 1 to 10 carbon atoms. Although not, tetraisopropoxy titanium, tetra-n-propoxy titanium, tetra-n-butoxy titanium, tetraethoxy titanium, tetraphenoxy titanium, or the like is preferably used. In addition, the aromatic polyvalent carboxylic acid represented by the general formula (II) to be reacted with the titanium compound or the anhydride thereof includes phthalic acid, trimellitic acid, hemimellitic acid, pyromellitic acid, or anhydrous anhydrides of these acids. The product is preferably used. When the titanium compound and the aromatic polyvalent carboxylic acid or anhydride thereof are reacted, all or part of the aromatic polyvalent carboxylic acid or anhydride thereof is dissolved in a solvent, and the titanium compound is dropped into this. What is necessary is just to make it react for 30 minutes or more at the temperature of 0-200 degreeC. Moreover, what is necessary is just to add the remaining aromatic polyhydric carboxylic acid or its anhydride after dripping a titanium compound as needed.

  As described above, the polyester composition of the present invention preferably uses a titanium compound and / or an aluminum compound as a polycondensation catalyst, but further uses a phosphorus compound as a stabilizer in order to further improve heat resistance and hue. It is preferable. Although there is no restriction | limiting in particular as this phosphorus compound, Preferably phosphoric acid, phosphorous acid, phosphonic acid, or phosphinic acid or these alkyl, aryl ester, and a phosphono acetate type compound are especially preferable. The phosphorus compound may be added to the polyester composition at any time after the ester exchange reaction or the esterification reaction is substantially completed, but usually immediately after the esterification reaction or the ester exchange reaction is completed. The polycondensation reaction is preferably carried out thereafter.

  Furthermore, it is preferable that the manufacturing method of the polyester composition of this invention is manufactured by adding an organic color adjusting agent in the arbitrary steps of the copolyester manufacturing process mentioned above. Especially, it is still more preferable that an organic color adjusting agent is added in the arbitrary steps until the polycondensation reaction process in a polyester composition manufacturing process is complete | finished. In particular, it is most preferable to add the organic color adjusting agent after completion of the esterification reaction or transesterification reaction.

  In producing such a polyester composition of the present invention, it can be produced according to a generally known method for producing a copolyester. Among them, the polyoxyalkylene glycol having a weight average molecular weight of 8000 or more is charged into the polymerization reactor before the polycondensation reaction is completed, preferably 90 to 40 minutes before the polymerization reaction. It is preferable to put in If it is introduced into the reactor at a time later than this time, the dispersibility of the polyoxyalkylene glycol may be deteriorated and the antistatic property may not be exhibited. On the other hand, if it is added at a time before this time, the polyoxyalkylene glycol starts to be decomposed by heat, which may induce thermal deterioration of the copolyester.

  The polyester fiber of the present invention can be obtained by spinning a polyester composition obtained by blending polyoxyalkylene glycol or the like by a known melt spinning method. In particular, the high-speed spinning method that does not require a drawing step can improve the productivity, reduce the cost by omitting the drawing step, improve the dyeability and easily knitting and knitting with other types of fibers, and can expand the application. Is preferable. In order to obtain a highly oriented yarn having sufficient practical properties only through the melt spinning step without passing through the drawing step, the winding speed is preferably 5200 m / min or more. At a winding speed of 5200 m / min or less, elongation is likely to occur in the weaving / knitting process, and stains and fabric quality are liable to occur. Since the yarn obtained by the high speed spinning method has a soft texture compared to the yarn obtained by the drawing method, it is particularly useful in the inner field such as foundation and lingerie.

  Furthermore, the polyester fiber of the present invention may be blended with antioxidants such as hindered phenols and phosphites, and may be blended with other additives such as colorants and matting agents as necessary. Also good. Further, the fabric obtained from the polyester fiber used in the present invention is obtained by knitting and knitting by a known method. When the specific polyester fiber is used in part, other materials such as ordinary polyester fibers are used as long as the antistatic property is not lost, but there are no particular restrictions on the types of other materials and the mixing method.

  Moreover, by attaching a known post-processing agent to the surface of the fabric, it is often preferable because the flexibility of the fabric is improved and the water absorption and antifouling properties are improved. The fabric of the present invention makes use of its excellent antistatic properties, low-temperature dyeability, soft texture, water absorption, antifouling properties, etc., in the inner field of foundations, lingerie, etc., and mixed with other types of fibers in the outer field. It can be developed for various uses.

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited thereto. In the following examples, “part” represents “part by mass”. In addition, the measured value in an Example is measured with the following method.
(A) Intrinsic viscosity of the polymer:
According to a conventional method, measurement was performed at 35 ° C. using o-chlorophenol as a solvent.
(A) Titanium, aluminum, antimony, phosphorus content:
Polyester composition soluble titanium element amount, aluminum element amount, antimony element amount, phosphorus element amount is a test in which a granular polyester composition sample is heated and melted on a steel plate and then flattened with a compression press. A molded body was prepared and obtained using a fluorescent X-ray apparatus (ZSX100e type, manufactured by Rigaku Corporation). However, regarding the amount of elemental titanium in the polyester composition to which titanium oxide was added as a matting agent, a sample in the polyester composition was dissolved in orthochlorophenol, and then extracted with 0.5 N hydrochloric acid. The extract was quantified using a Hitachi Z-8100 atomic absorption spectrophotometer. Here, when dispersion of titanium oxide was confirmed in the extract after extraction with 0.5 N hydrochloric acid, titanium oxide particles were precipitated using a centrifuge. Next, only the supernatant was recovered by the gradient method, and the same operation was performed. By these operations, even if the polyester composition contains titanium oxide, the titanium element soluble in the polyester can be quantified.
(C) Deposits generated on the spinneret:
The polyester composition is made into chips, melted at 290 ° C., discharged from a spinneret having a hole diameter of 0.15 mmφ and 12 holes, spun at 600 m / min for 2 days, and generated at the outer edge of the discharge outlet of the base. The height of the kimono layer was measured. As the height of the adhered layer increases, bending tends to occur in the filamentous flow of the melted polyester composition, and the moldability of the polyester decreases. That is, the height of the deposit layer generated in the spinneret is an index of the moldability of the polyester.
(D) Evaluation of deep color dyeability:
The test piece in which the fiber was formed on the fabric was immersed in a boiled 0.5% by mass sodium hydroxide aqueous solution and subjected to an alkali reduction treatment until the mass reduction rate of the fabric reached 20%. The taken-out fabric was washed with water, adjusted to a bath ratio of 1:50 with a 2% owf solution of a disperse dye Sumikaron Navy Blue S-2GL manufactured by Sumitomo Chemical Co., Ltd., and dyed at 110 ° C. for 1 hour. The dyed cloth was measured with a colorimetric color difference meter (CE-3000 type) manufactured by Greta Macbeth Co., and the deep chromaticity (K / S) was determined by the following Kubelka-Munk equation.
K / S = max [(1-R) ² / 2R]
In the above formula, K is an absorption coefficient and S is a scattering coefficient. R represents spectral reflectance, this spectrum is measured, and the maximum value is defined as deep chromaticity. In the present invention, 23 or more was judged good.
(E) Mass decrease start temperature of organic color matching agent:
Using a TAS-200 thermobalance manufactured by Rigaku Denki Kogyo Co., Ltd., the temperature was measured in a nitrogen atmosphere at a heating rate of 10 ° C./min according to JIS K7120.

(F) Frictional voltage:
A knitted fabric was produced using a small cylinder knitting machine (CR-B type, 3.5 inch × 220 needles) manufactured by Koike Seisakusho. This knitted fabric is washed for 5 minutes at 40 ° C. using 2 g / liter of detergent New Beads (manufactured by Kao Corporation), and rinsed twice at room temperature for 2 minutes. This was repeated 30 times as one cycle. Thereafter, the knitted fabric was charged for 30 seconds, and the discharge half-life was measured.
(G) Titanium dioxide, lithium, potassium, sodium, and aluminum contents:
The content of titanium dioxide in the polyester composition was calculated from the amount of titanium element measured using a 3270E type fluorescent X-ray apparatus manufactured by Rigaku Corporation. The contents of lithium, sodium, potassium and aluminum in titanium dioxide were analyzed by ICP after extracting titanium dioxide with hydrochloric acid. The ICP used was “Vista-PRO CCD multi-element simultaneous ICP emission spectroscopic analyzer” manufactured by Seiko Instruments Inc.
(H) Particle size measurement:
The average particle size and particle size distribution of the fine particles were measured with DLS-7000 manufactured by Otsuka Electronics Co., Ltd. and calculated as a mass fraction exceeding 0.1 μm from the particle size distribution.
(G) Polyoxyalkylene glycol content:
After dissolving the polymer sample in a deuterated trifluoroacetic acid / deuterated chloroform = 1/1 mixed solvent, JEOL A-600 superconducting FT-NMR manufactured by JEOL Ltd. was used to determine the nuclear magnetic resonance spectrum ( ¹ H- NMR) was measured, and the polyethylene glycol component content was quantified from the spectrum pattern according to a conventional method.
(Co) Monomethyl terephthalate (MMT) content:
The polyester composition was dissolved in hexafluoroisopropanol all day and night, methanol was added to reprecipitate the polymer. After removing the polymer, the polymer was diluted with methanol and measured with a high-performance liquid chromatograph 440 manufactured by Waters.

(Sa) Content of alkali metal sulfonate:
After the polyester composition sample is heated and melted on an aluminum plate, a test molded body having a flat surface is prepared with a compression press machine, and elemental sulfur is contained using a fluorescent X-ray apparatus (type 3270E manufactured by Rigaku Corporation). The amount was measured and calculated from the value.
(H) Hue (L ^* value, b ^* value):
The polyester composition chip was melted at 285 ° C. under vacuum for 10 minutes, formed into a plate having a thickness of 3.0 ± 1.0 mm on an aluminum plate, and immediately cooled in ice water. A time dry crystallization treatment was performed. Then, it placed on the white standard plate for color difference adjustment, and measured Hunter L ^* and b ^* of the plate surface using Minolta Co., Ltd. Hunter type color difference meter (CR-200 type). L ^* indicates lightness, and the larger the value, the higher the lightness, and b ^{* the} greater the value, the greater the degree of yellowing. Other detailed operations were performed according to JIS Z-8729.

[Reference Example 1] Synthesis of Titanium Catalyst A Tetra-n-butoxytitanium is added to an ethylene glycol solution (0.2% by mass) of trimellitic anhydride in an amount of ½ mol with respect to trimellitic anhydride, and under normal pressure in air. And kept at 80 ° C. for 60 minutes. Thereafter, it was cooled to room temperature, and the produced catalyst was recrystallized with 10 times the amount of acetone. The precipitate was filtered through filter paper and dried at 100 ° C. for 2 hours to obtain the target compound. This is designated as titanium catalyst A.

[Reference Example 2] Visible light absorption spectrum measurement of organic color adjusting agent (color adjusting dye), organic color adjusting agent preparation The color adjusting dye shown in Table 1 was made into a chloroform solution with a concentration of 20 mg / L at room temperature, and the optical path length was 1 cm. The quartz cell was filled with chloroform, and the control cell was filled with chloroform alone, and a visible light absorption spectrum in the visible light region of 380 to 780 nm was measured using a Hitachi spectrophotometer U-3010 type. In the case of mixing the two color adjusting dyes, the total concentration was 20 mg / L. The ratio of the absorbance at each wavelength of 400, 500, 600, and 700 nm to the maximum absorption wavelength and the absorbance at that wavelength was measured. Further, the thermal mass decrease start temperature of the powder color adjusting dye was measured. The results are shown in Table 1. In addition, when adding these organic color adjusters in the polyester production process in Examples and Comparative Examples, the solution is dissolved or dispersed at a temperature of 100 ° C. so as to have a concentration of 0.1% by mass with respect to the glycol solution used as a raw material. Prepared.

[Example 1]
700 parts of dimethyl terephthalate and 470 parts of ethylene glycol were used as a catalyst with 0.7 part of calcium acetate as a catalyst while heating from 140 ° C. to 240 ° C. in a nitrogen stream over 2 hours and 30 minutes to complete the transesterification reaction. Subsequently, 0.045 mass part of 56 mass% phosphoric acid aqueous solution was added to this reaction material, and the transesterification reaction was stopped. 1.8 parts of ethylene glycol slurry containing 20% by mass of titanium dioxide having an average particle size of 0.34 μm having the physical properties shown in Table 2 (0.3% by mass with respect to the copolyester), and the adjustment shown in Table 3 Colorant A 0.032 mass% ethylene glycol solution 0.4 part (0.6 mass ppm relative to copolymer polyester), titanium catalyst A 0.032 mass part prepared in Reference Example 1, and the blending amount shown in Table 1 Polyethylene glycol 4000 (manufactured by Nippon Oil & Fats Co., Ltd., weight average molecular weight 4000) was added so that the copolymerization rate was 4% by mass, and then the temperature was raised from 240 ° C. to 260 ° C. over 1 hour, and then for 1 hour. The pressure was reduced to 0.133 kPa or less while heating from 260 ° C. to 280 ° C. When the predetermined stirring power is reached, 0.8% by mass of sodium tetradecylsulfonate, 0.8% by mass of PEG 20000 (manufactured by Nippon Oil & Fats Co., Ltd.), antioxidant are obtained with respect to the obtained copolymer polyester. The reaction was terminated when the reaction was continued at 55 ° C. for 55 minutes at 280 ° C. and 0.133 kPa to obtain a polyester composition having an intrinsic viscosity of 0.64 dl / g. The titanium dioxide content was 0.3% by mass.

  Each of the obtained polyester compositions was dried by a conventional method, and passed through a filter with a nominal diameter (nominal opening) of 20 μm in a direct winding type high-speed spinning apparatus, while a spinning temperature of 290 ° C., a slit width of 0.11 mm, After spinning from a triaxial isometric spinneret having a slit length of 0.34 mm and a number of holes of 12, cooling and solidifying, a 33 dtex / 12f yarn was obtained. After preparing a knitted fabric, after carrying out the alkali weight reduction process of 20 mass%, easy dyeability was measured.

[Examples 2 to 4, Reference Example 5 ]
A polyester composition and fibers were obtained in the same manner as in Example 1 except that the types and amounts of titanium dioxide and organic color adjusting agent to be added were changed as shown in Tables 1 and 2. The titanium dioxide content was 0.3% by mass in all cases. These evaluation results are shown in Tables 2 and 3.

[Example 6]
In Example 1, in place of polyethylene glycol 4000 (manufactured by NOF Corporation, weight average molecular weight 4000), polyethylene glycol (manufactured by NOF Corporation, weight average molecular weight 4500) is similarly copolymerized at 4% by mass. A polyester composition and fibers were obtained in the same manner as in Example 1 except that the addition was performed as described above. These evaluation results are shown in Tables 2 and 3.

[Example 7]
In Example 1, a polyester composition and a fiber were obtained in the same manner as in Example 1 except that sodium tetradecylsulfonate was added to the copolymerized polyester at 1.0% by mass. These evaluation results are shown in Tables 2 and 3.

[ Example 8 ]
In Example 1, the same procedure as in Example 1 was used except that 0.0231 parts by mass of aluminum acetylacetonate was used instead of 0.032 parts by mass of titanium catalyst A prepared in Reference Example 1 when the copolymerized polyester was produced. Thus, a polyester composition and fibers were obtained. These evaluation results are shown in Tables 2 and 3.

[Comparative Example 1]
A polycondensation reaction was carried out in the same manner as in Example 1 except that polyoxyalkylene glycol or the like was not added to produce a polyester composition consisting only of ordinary polyethylene phthalate. The titanium dioxide content was 0.3% by mass.

[Comparative Example 2]
It was manufactured in the same manner as in Example 1 except that no organic color adjusting agent was added.

  According to the present invention, excellent durability antistatic property, good dyeability in dyeing at a pressure under normal pressure to 110 ° C., little deterioration in physical properties due to thermal deterioration, and complex spinning even when spinning by a high-speed spinning method. It is possible to provide a polyester composition capable of obtaining a fiber having good spinning properties without using a technique. Moreover, the polyester fiber and fabric obtained from this polyester composition are expected to have the effect of improving their flexibility and improving water absorption and antifouling properties. Furthermore, the fabric using the fiber of the present invention is made of the excellent antistatic property, low-temperature dyeability, flexible texture, water absorption, antifouling property, etc. It can be mixed and developed for various uses such as the outer field.

Claims (9)

A polyoxyalkylene glycol having a weight average molecular weight of 400 or more and less than 4500 is a polyester composition comprising a copolymerized polyester copolymerized in a proportion of 1 to 8% by mass,
(A) For the copolymer polyester,
(A) 0.03 mass% or more and 1 mass% or less of titanium dioxide,
(B) 0.1-10 mass ppm of organic color adjuster,
(C) 5 to 50 ppm by mass of monomethyl terephthalate,
(D) 0.5% by mass or more and 5% by mass or less of an alkali metal sulfonate, and
(E) Polyoxyalkylene glycol having a weight average molecular weight of 8000 or more
Contain,
(B) The average particle size of the titanium dioxide is 0.1 μm or more and 0.5 μm or less, and the mass fraction of particles having a particle size exceeding 1 μm is 0.5% by mass or more and 2% by mass or less, and Li, Na, Containing at least one element selected from the group of K and Al in the titanium dioxide from 0.01% by mass to 0.5% by mass,
(C) The composition of the organic color adjusting agent includes a blue color adjusting dye and a purple color adjusting dye in a mass ratio of 90:10 to 40:60, and the concentration of the organic color adjusting agent is 20 mg. When the visible light absorption spectrum in the wavelength range of 380 to 780 nm was measured for a chloroform solution of / L at an optical path length of 1 cm, the maximum absorption wavelength was in the range of 540 to 600 nm, and the absorbance at the maximum absorption wavelength was as follows. A polyester composition in which the absorbance ratio satisfies all of the following formulas (1) to (4).
0.00 ≦ A ₄₀₀ / A _max ≦ 0.20 (1)
0.10 ≦ A ₅₀₀ / A _max ≦ 0.70 (2)
0.55 ≦ A ₆₀₀ / A _max ≦ 1.00 (3)
0.00 ≦ A ₇₀₀ / A _max ≦ 0.05 (4)
[In the above formula, A ₄₀₀ , A ₅₀₀ , A ₆₀₀ and A ₇₀₀ are the absorbance in the visible light absorption spectrum at wavelengths of 400 nm, 500 nm, 600 nm and 700 nm, respectively, and A _max is the absorbance in the visible light absorption spectrum at the maximum absorption wavelength. Represents. ] Claim 1 polyester composition, wherein the weight average molecular weight of the polyoxyalkylene glycol is 600-4000. The polyester composition according to any one of claims 1 to 2, wherein the alkali metal sulfonate is an alkylsulfonic acid sodium salt. The polyester composition according to any one of claims 1 to 3 , wherein the polyester composition is produced using a polycondensation catalyst containing a titanium compound. The titanium compound is a product obtained by reacting a compound represented by the following general formula (I) with an aromatic polyvalent carboxylic acid or acid anhydride represented by the following general formula (II). The polyester composition according to claim 4 .

[In the above formula, R ₁ , R ₂ , R ₃ and R ₄ each independently represent an alkyl group having 1 to 10 carbon atoms or a phenyl group, m represents an integer of 1 to 4, and m is 2 In the case of 3 or 4, 2, 3 or 4 R ₂ and R ₃ may be different from each other. ]

[In the above formula, q represents an integer of 2 to 4. ] Seiirozai is, under a nitrogen atmosphere, according to claim 1 to 5 mass decrease start temperature when measured by a thermobalance at a heating rate of 10 ° C. / min condition is selected from orthochromatic dye is 250 ° C. or higher The polyester composition according to any one of the above. It is a copolymerized polyester in which a polyoxyalkylene glycol having a weight average molecular weight of 400 or more and less than 4500 is copolymerized at a ratio of 1% by mass to 8% by mass,
(A) For the copolymer polyester,
(A) 0.03 mass% or more and 1 mass% or less of titanium dioxide,
(B) 0.1-10 mass ppm of organic color adjuster,
(C) 5 to 50 ppm by mass of monomethyl terephthalate,
(D) 0.5% by mass or more and 5% by mass or less of an alkali metal sulfonate, and
(E) Polyoxyalkylene glycol having a weight average molecular weight of 8000 or more
Contain,
(B) The average particle size of the titanium dioxide is 0.1 μm or more and 0.5 μm or less, and the mass fraction of particles having a particle size exceeding 1 μm is 0.5% by mass or more and 2% by mass or less, and Li, Na, Containing at least one element selected from the group of K and Al in the titanium dioxide from 0.01% by mass to 0.5% by mass,
(C) The composition of the organic color adjusting agent includes a blue color adjusting dye and a purple color adjusting dye in a mass ratio of 90:10 to 40:60, and the concentration of the organic color adjusting agent is 20 mg. When the visible light absorption spectrum in the wavelength range of 380 to 780 nm was measured for a chloroform solution of / L at an optical path length of 1 cm, the maximum absorption wavelength was in the range of 540 to 600 nm, and the absorbance at the maximum absorption wavelength was as follows. The polyester composition satisfying all the following mathematical formulas (1) to (4), and the organic colorant is added at any stage until the polycondensation reaction step in the polyester composition production process is completed. A method for producing a polyester composition.
0.00 ≦ A ₄₀₀ / A _max ≦ 0.20 (1)
0.10 ≦ A ₅₀₀ / A _max ≦ 0.70 (2)
0.55 ≦ A ₆₀₀ / A _max ≦ 1.00 (3)
0.00 ≦ A ₇₀₀ / A _max ≦ 0.05 (4)
[In the above formula, A ₄₀₀ , A ₅₀₀ , A ₆₀₀ and A ₇₀₀ are the absorbance in the visible light absorption spectrum at wavelengths of 400 nm, 500 nm, 600 nm and 700 nm, respectively, and A _max is the absorbance in the visible light absorption spectrum at the maximum absorption wavelength. Represents. ] The method for producing a polyester composition according to claim 7, wherein titanium dioxide is added before the polycondensation reaction step, during the polycondensation reaction step, and after the polycondensation reaction step. The polyester fiber formed by melt-spinning the polyester composition as described in any one of Claims 1-6 .