Irregularly shaped cross-section polyester fiber

Abstract

To provide a polyester fiber that can be dyed with a cationic dye under normal pressure and has a complicated cross-sectional shape with a convex part on an outer periphery.SOLUTION: An irregular shape cross-section polyester fiber is composed of a polyester resin containing a specific amount of an aromatic dicarboxylic acid having a metal sulfonate group and an aliphatic dicarboxylic acid having 5 to 10 carbon atoms in a total acid component, the irregular shape cross-section polyester fiber exhibits an irregular shape cross-section shape having one or more convex parts on an outer periphery in a cross section perpendicular to the longitudinal direction of yarn, and the irregular shape cross-section polyester fiber (a) contains an alkaline earth metal compound and a phosphorus compound, and satisfies (b) a strength of 1.4 cN / dtex or more and (c) a crystallinity of 11 to 15%.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a specially shaped cross-section polyester fiber that can be dyed with cationic dyes at atmospheric pressure, and to textile products using the same polyester fiber. It also relates to a method for producing the same polyester fiber. [Background technology]

[0002] Polyester fibers, particularly polyethylene terephthalate fibers, are widely used in clothing and industrial applications due to their excellent heat resistance, chemical resistance, and mechanical properties. However, because of their rigid fiber structure, dyeing typically requires high temperature and pressure. Therefore, in order to obtain polyester fibers that can be dyed with cationic dyes and can be cationically dyed even under normal pressure, a method of copolymerizing a third component such as adipic acid or isophthalic acid in addition to a cationic dyeable component such as 5-sodium sulfoisophthalic acid is known from Patent Documents 1 and 2.

[0003] Furthermore, Patent Document 3 shows that when a polyester resin composition copolymerized with 5-sodium sulfoisophthalic acid and adipic acid is used to produce fibers, by including specific amounts of internal particles formed from alkaline earth metal salts of carboxylic acids and phosphate esters, as well as germanium oxide, in the resin composition, it is possible to dye it with cationic dyes and produce polyester fibers with low single-fiber fineness with good operability.

[0004] On the other hand, in response to the diversification of consumer needs in recent years, polyester fibers are in demand for various cross-sectional shapes to meet market requirements. In particular, fibers with special irregular cross-sectional shapes that have one or more protrusions on the fiber surface can be woven or knitted to improve sweat absorption and diffusion, and provide excellent coolness (crispness and dryness). However, when producing polyester fibers using a polyester resin composition copolymerized with 5-sodium sulfisophthalic acid and aliphatic dicarboxylic acid such as adipic acid, it is presumed that the crystallinity of the resin composition tends to decrease, and therefore, no fibers with the special irregular cross-sectional shape described above have yet been proposed. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Special Publication No. 57-032139 [Patent Document 2] Japanese Patent Application Publication No. 08-269820 [Patent Document 3] Japanese Patent Publication No. 2013-18802 [Overview of the project] [Problems that the invention aims to solve]

[0006] The objective of the present invention is to solve the above-mentioned problems and to provide a polyester fiber that can be dyed with cationic dyes under normal pressure and has a complex cross-sectional shape with one or more protrusions on its outer circumference. [Means for solving the problem]

[0007] The present inventors conducted diligent studies to solve the aforementioned problems and, as a result, discovered that the desired fiber can be obtained by controlling the manufacturing conditions during melt spinning of polyester fibers and making the degree of crystallinity of the resulting polyester fibers within a specific range, thus arriving at the present invention. In other words, the present invention is summarized as follows:

[0008] (i) A polyester fiber made of a polyester resin, wherein when the total amount of all acid components constituting the polyester is 100 mol%, it contains 80 mol% or more of terephthalic acid, 0.5 to 5 mol% of aromatic dicarboxylic acid having a metal sulfonate group and 2 to 18 mol% of aliphatic dicarboxylic acid having 5 to 10 carbon atoms, and when the total amount of all glycol components is 100 mol%, it contains 80 mol% or more of ethylene glycol, and is characterized by having an irregular cross-sectional shape with one or more protrusions on the outer circumference in a cross section perpendicular to the longitudinal direction of the yarn, and satisfying all of the following characteristics (a) to (c). (a) containing alkaline earth metal compounds and phosphorus compounds (b) Fiber strength of 1.4 cN / dtex or higher (c) Obtained by the method described below Degree of crystallinity 12 ~ 14 % Crystallinity Using a differential scanning calorimeter, 8.5 mg of the fiber sample is heated from 25°C to 280°C at a rate of 20°C / min, and the values ​​obtained (ΔHm, ΔHc) are calculated using the following formula. Crystallinity = {(ΔHm - ΔHc)} / 140.2} × 100 (%) (ΔHm represents the heat at the melting point, and ΔHc represents the heat at which crystallization occurs with heating) A textile product that uses at least a portion of the irregularly shaped cross-section polyester fibers described in (b) and (a). [Effects of the Invention]

[0009] The irregularly shaped polyester fiber of the present invention contains an aromatic dicarboxylic acid having a specific amount of metal sulfonate groups and an aliphatic dicarboxylic acid having 5 to 10 carbon atoms, and therefore can be dyed with cationic dyes under normal pressure conditions. Furthermore, it exhibits an irregular cross-sectional shape with one or more protrusions on its outer circumference and possesses sufficient strength, making it possible to obtain processed yarns and woven or knitted fabrics that maintain the irregular cross-sectional shape. Woven or knitted fabrics using the irregularly shaped cross-section polyester fibers of the present invention improve sweat absorption and diffusion, and provide excellent coolness (crispness and dryness), making them suitable for clothing applications. Furthermore, because they have excellent color development and bulkiness, they can be widely used in interior products such as carpets and curtains, as well as various industrial materials. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram showing an embodiment of the cross-section of the profiled polyester fiber (monofilament) of the present invention. [Figure 2] This is a schematic diagram showing an embodiment of the cross-section of the profiled polyester fiber (monofilament) of the present invention. [Figure 3] This is a schematic diagram showing an embodiment of the cross-section of the profiled polyester fiber (monofilament) of the present invention. [Figure 4] This is a schematic diagram showing an embodiment of the cross-section of the profiled polyester fiber (monofilament) of the present invention. [Figure 5] This is a schematic diagram showing an embodiment of the cross-section of the profiled polyester fiber (monofilament) of the present invention.

Embodiments for Carrying out the Invention

[0011] s Hereinafter, the present invention will be described in detail. The polyester resin composition constituting the profiled polyester fiber of the present invention (hereinafter sometimes abbreviated as profiled fiber) contains terephthalic acid as a main component as an acid component in the polyester resin, and contains a specific amount of an aromatic dicarboxylic acid having a metal sulfonate group and an aliphatic dicarboxylic acid having 5 to 10 carbon atoms. By copolymerizing an aromatic dicarboxylic acid having a metal sulfonate group, cationic dyeability can be imparted to the polyester resin.

[0012] The polyester resin (hereinafter sometimes referred to as "polyester resin") in the polyester resin composition constituting the irregularly shaped cross-section fibers of the present invention contains 0.5 to 5 mol% of aromatic dicarboxylic acid having a metal sulfonate group, when the total amount of all acidic components is 100 mol%. The aromatic dicarboxylic acid having a metal sulfonate group is preferably included as a copolymer component, and more preferably copolymerized at 0.8 to 3.0 mol%. The aromatic dicarboxylic acid having a metal sulfonate group functions as a dyeing seat (number of reactive groups that react with the cationic dye) for cationic dyes, thereby enabling the irregularly shaped cross-section fibers of the present invention to be dyed with cationic dyes. If the content (copolymerization amount) of aromatic dicarboxylic acid having a metal sulfonate group is less than 0.5 mol%, the dyeing surface for cationic dyes is insufficient, and the resulting irregularly shaped cross-section fibers do not achieve sufficient dyeability for cationic dyes. On the other hand, if the concentration exceeds 5 mol%, the melt viscosity of the polyester tends to become too high during the polycondensation process, making it difficult to sufficiently increase the degree of polymerization. As a result, the resulting fiber has low yarn strength.

[0013] Examples of aromatic dicarboxylic acids having a metal sulfonate group include 5-sodium sulfisophthalic acid, 5-potassium sulfisophthalic acid, 5-lithium sulfisophthalic acid, sodium sulfonaphthalenedicarboxylic acid, sodium sulfophenyldicarboxylic acid, and 5-sodium sulfoterephthalic acid. However, in the present invention, 5-sodium sulfisophthalic acid is preferably used in terms of color development by cationic dyes, operability during melt spinning, and cost. These acids may be used as they are, or ester-forming derivatives may be used, and among these, esters with ethylene glycol are preferably used in terms of operability and other factors.

[0014] Furthermore, the acid components constituting the polyester resin contain 2 to 18 mol% of aliphatic dicarboxylic acids having 5 to 10 carbon atoms, when the total amount of all acid components is 100 mol%. It is preferable that the aliphatic dicarboxylic acids having 5 to 10 carbon atoms are included as copolymerization components, and it is particularly preferable that they are copolymerized at 5.0 to 12.0 mol%. By copolymerizing an appropriate amount of aliphatic dicarboxylic acids having 5 to 10 carbon atoms, disorder is created in the crystals of the polyester (polyethylene terephthalate), and the orientation of the amorphous regions is reduced, which facilitates the penetration of dyes into the fibers. This makes it possible to impart cationic dyeability to irregularly shaped cross-section fibers under normal pressure conditions. It is also possible to soften the texture of irregularly shaped cross-section fibers. If the content (copolymer amount) of aliphatic dicarboxylic acids with 5 to 10 carbon atoms is less than 2 mol%, the dyeability under normal pressure conditions will be insufficient. On the other hand, if it exceeds 18 mol%, the thermal stability of the polyester resin decreases, resulting in low yarn strength when it is made into fibers. Examples of aliphatic dicarboxylic acids having 5 to 10 carbon atoms include glutaric acid, adipic acid, pimelic acid, suberic acid, and sebacic acid. In the present invention, adipic acid is preferably used from the viewpoint of operability during melt spinning and cost.

[0015] The polyester resin contains 80 mol% or more of terephthalic acid, preferably between 85 and 97.5 mol%, when the total amount of all acidic components is 100 mol%. If the proportion of terephthalic acid is less than 80 mol%, the crystallinity of the polyester resin decreases and the melting point becomes lower, which may reduce operability in melt spinning and drawing. On the other hand, if the proportion of terephthalic acid exceeds 97.5 mol%, the copolymerization amount of aromatic dicarboxylic acids having metal sulfonate groups and aliphatic dicarboxylic acids having 5 to 10 carbon atoms decreases, so the effect of dyeability with cationic dyes under normal pressure conditions becomes smaller.

[0016] In polyester resins, acid components other than terephthalic acid, aromatic dicarboxylic acids having a metal sulfonate group, and aliphatic dicarboxylic acids having 5 to 10 carbon atoms include isophthalic acid, phthalic acid, phthalic anhydride, naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, dodecanedioic acid, dimer acid, and also trimellitic anhydride, trimellitic acid, pyromellitic acid, 1,4-cyclohexanedicarboxylic acid, dimer acid, etc. Two or more of these may be used in combination, and ester-forming derivatives of these acids may also be used.

[0017] When the total amount of glycol components in a polyester resin is 100 mol%, the ethylene glycol content is preferably 80 mol% or more, and more preferably 85 mol% or more. If the proportion of ethylene glycol is less than 80 mol%, the crystallinity of the polyester resin decreases and the melting point becomes lower, resulting in reduced operability during melt spinning and drawing.

[0018] Polyester resins may contain glycol components other than ethylene glycol in their total glycol composition. Specific examples include diethylene glycol, neopentyl glycol, 1,4-butanediol, 1,2-propylene glycol, 1,5-pentanediol, 1,3-propanediol, 1,6-hexamethylenediol, diethylene glycol, 1,4-cyclohexanedimethanol, dimer diol, butylethylpropanediol, 2-methyl-1,3-propanediol, trimethylolpropane, glycerin, pentaerythritol, ethylene oxide adducts of bisphenol A or bisphenol S, etc.

[0019] The irregularly shaped cross-section polyester fiber of the present invention satisfies all of the following characteristics (a) to (c). (a) containing alkaline earth metal compounds and phosphorus compounds (b) Fiber strength of 1.4 cN / dtex or higher (c) Crystallinity of the fibers is 11-15% By satisfying these characteristics, it is possible to obtain polyester fibers that are high in strength and have a complex cross-sectional shape. Furthermore, when woven or knitted fabrics are made using the irregularly shaped cross-sectional polyester fibers of the present invention, they exhibit excellent water absorption and diffusion properties, and provide a superior cooling sensation (crispness and dryness). These irregularly shaped cross-sectional polyester fibers that satisfy these characteristics can be obtained by the manufacturing method of the present invention, which will be described later.

[0020] First, condition (a) states that the irregularly shaped cross-section polyester fiber contains an alkaline earth metal compound and a phosphorus compound. In the present invention, by including generated particles formed by the alkaline earth metal compound and the phosphorus compound in the polyester resin composition constituting the irregularly shaped cross-section fiber, it is possible to obtain an irregularly shaped cross-section polyester fiber that exhibits excellent operability in the spinning and drawing process and subsequent post-processing process, and that shows dyeability with cationic dyes under normal pressure conditions, exhibiting a complex irregular cross-section.

[0021] The generated particles in this invention are different from known inert fine particles such as silica fine particles. They are particles formed when the alkaline earth metal compound and phosphorus compound react with each other by adding them individually to the manufacturing stage (synthesis reaction system) of the polyester resin composition without reacting them beforehand.

[0022] [Alkaline earth metal compounds] In the present invention, it is particularly preferable to use alkaline earth metal salts of carboxylic acids as the alkaline earth metal compounds, and specific examples include magnesium acetate, calcium acetate, magnesium oxalate, calcium propynate, calcium stearate, magnesium stearate, calcium benzoate, manganese acetate, and the like.

[0023] When a magnesium salt of a carboxylic acid is used, the particle size of the resulting particles formed in the polyester resin is relatively small, resulting in good stability during the polyester fiber spinning process. Furthermore, since the refractive index of the resulting particles is close to that of the polyester resin, the transparency of the polyester resin composition containing the dispersed particles is increased, which is preferable. Among these, magnesium acetate is particularly preferred from the viewpoint of handling and cost.

[0024] [Phosphorus compounds] As described above, the phosphorus compound in the present invention reacts with alkaline earth metal compounds to form particles, contributing to the stability of the yarn spinning process for irregularly shaped cross-section polyester fibers. While it is known that phosphoric acid, phosphorous acid, phosphonic acids, phosphinic acids, etc., can also react, it is preferable to use phosphoric acid esters in the present invention. By using phosphoric acid esters, the particle size of the generated particles becomes relatively small, resulting in good stability in the yarn spinning process for irregularly shaped cross-section polyester fibers. In addition, since the refractive index of the generated particles is close to that of the polyester resin, the transparency of the polyester resin composition containing the generated particles is increased. Among these, the use of triethyl phosphate (triethyl phosphate) is particularly preferred.

[0025] In the present invention, it is most preferable to use magnesium acetate as the alkaline earth metal compound and triethyl phosphate as the phosphorus compound in combination.

[0026] In the present invention, the average particle size of the generated particles is preferably 0.01 to 3.0 μm, and more preferably 0.02 to 1.5 μm. If the average particle size is 0.01 μm or more, the generated particles are not too fine, which improves the slipperiness and running properties of the fibers, resulting in good process passability. Furthermore, if the average particle size is 3.0 μm or less, the filter that filters the molten polymer when spinning irregularly shaped cross-section polyester fibers will not become clogged, and pressure increases or yarn breakage can be suppressed. The average particle size of the generated particles can be controlled to the above range, for example, by optimizing the combination of alkaline earth metal compounds and phosphorus compounds, or by adjusting the amounts of alkaline earth metal compounds and phosphorus compounds added.

[0027] The polyester resin composition of the present invention may contain alkali metal compounds and germanium oxides in addition to alkaline earth metal compounds and phosphorus compounds.

[0028] Alkali metal compounds are, in particular, alkali metal salts of carboxylic acids, and specific examples include lithium acetate, sodium acetate, potassium acetate, lithium benzoate, sodium benzoate, or potassium benzoate. Among these, lithium acetate is preferred because it allows for an optimal average particle size of the resulting particles and suppresses by-products during the polymerization reaction of polyester.

[0029] Examples of germanium oxides include germanium dioxide, germanium hydroxide, and germanium tetrachloride, but germanium dioxide is preferred when considering safety.

[0030] Germanium oxide suppresses the generation of significantly large particles, thereby reducing fuzzing during the spinning of irregularly shaped polyester fibers and minimizing yarn unevenness. Furthermore, it suppresses dullness caused by the precipitation of metallic antimony, resulting in a resin composition with good color tone. Consequently, the resulting irregularly shaped polyester fibers also exhibit reduced dullness, resulting in highly glossy polyester fibers with excellent color tone.

[0031] In the present invention, germanium oxide is preferably added to the polycondensation reaction vessel as an ethylene glycol solution. The concentration of the solution is not particularly limited, but it is preferable that it is at a concentration that allows for complete dissolution.

[0032] In this invention, the amount of germanium oxide added is preferably 20 ppm to 150 ppm, and more preferably 30 ppm to 120 ppm, in terms of the amount of germanium atoms relative to the polyester resin composition. By setting the amount of addition within the above range, fine and homogeneous particles are obtained, and even polyester fibers with complex, irregular cross-sections have good spinnability.

[0033] As a condition for (b), the tensile strength of the fiber must be 1.4 cN / dtex or higher, and more preferably 1.5 cN / dtex or higher. A tensile strength of 1.4 cN / dtex or higher makes it less likely for fuzzing and yarn breakage to occur during stretching and false twisting processes, resulting in sufficient strength for practical use. Furthermore, when weaving or knitting using fibers with irregular cross-sections, woven or knitted fabrics can be obtained with good operability without yarn breakage.

[0034] The elongation at break is preferably 120% or more, more preferably 120-200%, and more preferably 130-170%. By setting the elongation at break within the above range, for example, a woven or knitted fabric obtained using some irregularly shaped cross-section polyester fibers becomes strong against friction between fibers, less prone to tearing, and has excellent durability.

[0035] (c) Condition: The degree of crystallinity of the fibers ga 1 2-14% ru. Because the degree of crystallinity falls within this numerical range, the resulting polyester fibers can exhibit the desired irregular cross-sectional shape and also possess appropriate strength. Therefore, even when the resulting fibers are subjected to stretching or false-twisting, the irregular cross-sectional shape of the fibers can be maintained when processing yarns or woven / knitted fabrics are obtained. Crystallinity is 1 2 If the crystallinity is less than 1%, it is presumed that the amount of amorphous material in the fiber will increase, resulting in a softer polyester resin, but the strength of the irregularly shaped cross-section polyester fiber will decrease, making it unsuitable for practical use. On the other hand, if the degree of crystallinity is 1 4If the percentage exceeds %, it becomes difficult to spin fibers that exhibit the desired irregular cross-section. Furthermore, when the resulting fibers are subjected to stretching or false-twisting processes, fuzzing and breakage are more likely to occur, resulting in poor operability. In addition, dyeability may be poor. In the present invention, it is important that the irregularly shaped polyester fibers satisfy the above-mentioned range of crystallinity. By having a crystallinity within this range, even fibers with complex irregular cross-sections will have excellent operability and strength. In the present invention, it is possible to achieve the above-mentioned range of crystallinity by employing the manufacturing method described later. In this invention, the degree of crystallinity refers to the degree of crystallinity of a specially shaped cross-section polyester fiber, measured using a measurement method described later.

[0036] In this invention, the degree of crystallinity is calculated using the following formula: A differential scanning calorimeter (Diamond DSC, PerkinElmer) is used to heat 8.5 mg of the sample (irregular cross-section polyester fiber) from 25°C to 280°C at a rate of 20°C / min, and the value obtained is used to calculate the degree of crystallinity (Xc) using the following formula. Crystallinity (Xc)={(ΔHm-ΔHc)} / 140.2}×100(%) (ΔHm represents the heat required for the melting point, and ΔHc represents the heat required for crystallization through heating.)

[0037] The single fiber fineness of the irregularly shaped cross-section polyester fiber of the present invention is preferably 0.3 to 4.0 dtex, and more preferably 0.6 to 3.0 dtex, from the viewpoint of spinnability and handling.

[0038] The single yarn constituting the irregularly shaped polyester fiber of the present invention has one or more protrusions on its outer circumference in the cross-sectional shape obtained by cutting the single yarn perpendicular to its longitudinal direction. Examples of cross-sectional shapes having one or more protrusions on the outer circumference include arrow-shaped (Figure 1), single-arrow-shaped (Figure 2), Y-shaped (Figure 3), multi-lobed cross-sectional shapes as shown in Figure 4, star-shaped and cross-shaped shapes as shown in Figure 5, etc., when the single yarn is cut perpendicular to its longitudinal direction. In this cross-sectional shape, from the viewpoint of water absorption and diffusion, it is preferable to have 2 to 10 protrusions, and more preferably 2 to 8 protrusions.

[0039] The irregularly shaped polyester fiber of the present invention is preferably composed of a flattened core and a convex portion having a flattening degree of 2.0 to 6.0 in the fiber cross-section, and the ratio of the thickness of the convex portion to the core, i.e., (height of the convex portion) / (length of the short side of the core), is 0.5 to 2.0.

[0040] The preferred shape of the irregular cross-section in the present invention will be further explained with reference to Figures 1 to 3. The flattened core 1, which has a long side and a short side in the irregular cross-section, is the core part in the fiber cross-section. The convex part 2 in the irregular cross-section connects to the core to form a convex shape. As shown in Figures 1 to 3, the cross-sectional shapes of the fiber include arrow-shaped (Figure 1), single-arrow-shaped (Figure 2), Y-shaped (Figure 3), and multi-lobed cross-sectional shapes. In Figures 1 to 3, 3 indicates the long side of the core, 4 indicates the short side of the core, and 5 indicates the height of the convex part. The height of the convex part 5 refers to the distance between the highest point of the part protruding from the flattened part of the fiber cross-section and the flattened part.

[0041] The fiber cross-section shown in Figure 1 has a flattened base 1 with a long side 3 and a short side 4, and a pair of protrusions 2, 2 are formed at one end of the base 1, projecting in opposite directions, resulting in an arrow-shaped cross-section. The fiber cross-section shown in Figure 2 has a flattened base 1 with a long side 3 and a short side 4, and the protrusions are formed so as to project from one end of the base 1 toward the short side of the base 1, resulting in a single arrow-shaped cross-section. The fiber cross-section shown in Figure 3 has a flattened base 1 with a long side 3 and a short side 4, and a pair of protrusions 2, 2 are formed at one end so as to split into two, resulting in a Y-shaped cross-section.

[0042] In the present invention, as described above, the main part of the irregularly shaped cross-section is preferably a flattened shape having a flattening degree of 2.0 to 6.0, more preferably 3.7 to 6.0, and even more preferably 4.0 to 5.8. In this invention, by using a modified cross-section polyester fiber having one or more protrusions on the outer circumference of the single-fiber cross-section and a flatness of 2.0 to 6.0, fine gaps are formed between the fibers. When this modified cross-section polyester fiber is used to make woven or knitted fabrics, it is possible to improve the absorption and diffusion of sweat and provide an excellent feeling of coolness (crispness and dryness). The degree of flatness is obtained by the following formula (1), and refers to the value obtained by dividing the length of the longer side of the main body by the length of the shorter side. Flatness = (Length of the long side of the core) / (Length of the short side of the core) ... (1)

[0043] In the present invention, as described above, the thickness ratio between the convex portion and the core of the irregularly shaped cross-section polyester fiber is preferably 0.5 to 2.0, and more preferably 1.0 to 2.0. By setting this thickness ratio between the convex portion and the core to 0.5 to 2.0, the height of the convex portion becomes within a more appropriate range, thereby obtaining better water absorption and diffusion properties. The above thickness ratio is the ratio of the height of the convex portion to the length of the short side of the core, and refers to the thickness ratio between the convex portion and the core derived from the following formula (2). The ratio of the thickness of the protrusion to the core = (height of the protrusion) / (length of the shorter side of the core) ... (2)

[0044] The irregularly shaped cross-section polyester fiber of the present invention is obtained by spinning a polyester resin composition that contains a specific amount of aromatic dicarboxylic acid having a metal sulfonate group and aliphatic dicarboxylic acid having 5 to 10 carbon atoms, and further contains particles formed by the reaction of an alkaline earth metal compound and a phosphorus compound. By employing the manufacturing method described later and setting the degree of crystallinity to a suitable range, it is possible to obtain an irregularly shaped cross-section polyester fiber that exhibits cationic dyeability under normal pressure, has excellent strength, etc., and has a complex cross-sectional shape with one or more protrusions on the outer circumference of the single filament cross-section.

[0045] The method for producing irregularly shaped cross-section polyester fibers of the present invention is described below. The present invention provides a manufacturing method comprising: a step (I) of esterifying a dicarboxylic acid component and a diol component to produce a polyester oligomer; a step (II) of adding an aromatic dicarboxylic acid having a metal sulfonate group, an aliphatic dicarboxylic acid having 5 to 10 carbon atoms, a phosphorus compound, and an alkaline earth metal compound to the polyester oligomer, and then carrying out a polycondensation reaction to obtain a polyester resin composition; and a step (III) of spinning the polyester resin composition to obtain a polyester fiber with a unique cross-section.

[0046] <Process (I)> As the dicarboxylic acid, terephthalic acid can be mainly used. Other components may be copolymerized depending on the purpose, as long as they do not impair the effects of the present invention. Examples of components other than terephthalic acid include isophthalic acid, phthalic acid, phthalic anhydride, 5-tetrabutylphosphonium sulfisoisophthalic acid, 4,4'-biphenyldicarboxylic acid, p-hydroxybenzoic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, or 1,4-cyclohexyldicarboxylic acid.

[0047] Ethylene glycol can be used as the diol component. Other components may be copolymerized depending on the purpose, as long as they do not impair the effects of the present invention. Examples of components other than ethylene glycol include 1,3-propanediol, 1,4-butanediol, diethylene glycol, 1,2-propylene glycol, 2,2-dimethyl-1,3-propanediol (neopentylene glycol), dipropylene glycol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dimethylolpropionic acid, poly(ethylene oxide) glycol, or poly(tetramethylene oxide) glycol.

[0048] In step (I), a dicarboxylic acid (a dicarboxylic acid mainly composed of terephthalic acid) and a diol (a diol mainly composed of ethylene glycol) are esterified to obtain a polyester oligomer. Here, a polyester oligomer is defined as a compound in which, when the dicarboxylic acid and diol components are terephthalic acid and ethylene glycol, respectively, bis(2-hydroxyethyl) terephthalate is included, and furthermore, one molecule contains two or more repeating units of ethylene terephthalate, and the intrinsic viscosity, molecular weight, and degree of polymerization have not yet increased to the point where it can be called polyethylene terephthalate, and the terminal end is a carboxyl group or a hydroxyethyl group. The esterification reaction can be carried out at a temperature of 250°C for 3 to 8 hours until such a polyester oligomer is produced. The reaction rate of the esterification reaction can be measured by measuring the amount of water produced.

[0049] Polypropylene oligomers may be copolymerized with polyvalent carboxylic acids such as trimellitic acid, trimesic acid, trimellitic anhydride, pyromellitic acid, and monopotassium trimellitic acid, as well as polyvalent hydroxy compounds such as glycerin, pentaerythritol, sodium dimethylolethylsulfonate, and potassium dimethylolpropionate, within the limits necessary to achieve the objectives of the present invention.

[0050] <Process (II)> The above polyester oligomer is mixed with an aromatic dicarboxylic acid having a metal sulfonate group, an aliphatic dicarboxylic acid having 5 to 10 carbon atoms, an alkaline earth metal compound, and a phosphorus compound, and then a polycondensation reaction is carried out to obtain a polyester resin composition. In step (II), the aromatic dicarboxylic acid having a metal sulfonate group and the aliphatic dicarboxylic acid having 5 to 10 carbon atoms are copolymerized, and along with the polycondensation reaction, a reaction occurs between the phosphorus compound and the alkaline earth metal compound, forming the above-mentioned particles that are insoluble in the polyester resin composition.

[0051] Aromatic dicarboxylic acids having a metal sulfonate group can be added at any stage in the synthesis of polyester resins. For example, when 5-sodium sulfisophthalic acid is used as the aromatic dicarboxylic acid having a metal sulfonate group, common methods include adding 5-sodium sulfisophthalic acid powder at the start of the esterification reaction between terephthalic acid and ethylene glycol, and adding it to bishydroxyethyl terephthalate obtained by the esterification reaction between terephthalic acid and ethylene glycol as a dispersion or solution of alkylene glycol esters such as dimethyl 5-sodium sulfisophthalate or ethylene glycol 5-sodium sulfisophthalate.

[0052] Furthermore, aliphatic dicarboxylic acids having 5 to 10 carbon atoms can be added at any stage in the synthesis of polyester resins. For example, when using adipic acid as the aliphatic dicarboxylic acid having 5 to 10 carbon atoms, it is common to add adipic acid powder at the start of the esterification reaction between terephthalic acid and ethylene glycol, or to add adipic acid or bis(2-hydroxy)adipate dispersion or solution to bishydroxyethyl terephthalate obtained by the esterification reaction between terephthalic acid and ethylene glycol.

[0053] Furthermore, the polyester composition resin may contain small amounts of additives as needed, such as matting agents, pigments, antioxidants, fluorescent whitening agents, antistatic agents, antibacterial agents, ultraviolet absorbers, light stabilizers, heat stabilizers, flame retardants, etc.

[0054] Regarding the order in which phosphorus compounds and alkaline earth metal compounds are added, the phosphorus compounds may be added first, or they may be added later, or they may be mixed together and added simultaneously.

[0055] The amount of alkaline earth metal compound added is 5 × 10⁻⁶ per mole of the acidic component constituting the polyester. -4 ~70×10 -4 It is preferably in moles, and more preferably 20 × 10 -4 ~60×10-4 is in moles. When the content is 5×10 -4 or more, a sufficient number of generated particles can be obtained to improve the stability of the polyester fiber spinning process. When it is 70×10 -4 or less in moles, the generation of coarse particles can be suppressed, so clogging of the filter for filtering the molten polyester resin composition during spinning does not occur, and the stability of the spinning process of the profiled cross-section polyester fiber can be maintained well.

[0056] The addition amount of the phosphorus compound is preferably 1×10 -4 ~100×10 -4 moles, more preferably 20×10 -4 ~90×10 -4 moles. When the content is 1×10 -4 or more in moles, a sufficient number of generated particles can be obtained to improve the stability of the polyester fiber spinning process. When it is 100×10 -4 or less in moles, the generation of coarse generated particles can be suppressed, so clogging of the filter for filtering the molten polyester resin composition during spinning does not occur, and the stability of the spinning process of the profiled cross-section polyester fiber can be maintained well. In addition, from the viewpoint of spinning stability, the molar ratio of the alkaline earth metal compound to the phosphorus compound is preferably (alkaline earth metal compound) / (phosphorus compound)=0.5~1.5.

[0057] Next, a polycondensation catalyst (e.g., an ethylene glycol solution) is added and a polycondensation reaction is carried out to obtain a polyester resin composition. Additives such as copolymer monomers or color inhibitors may be added to the polycondensation reaction system as an ethylene glycol solution or dispersion, as needed. In this case, the polycondensation reaction is initiated by distillation of the ethylene glycol (removal of ethylene glycol under reduced pressure), and the reaction is carried out while continuing the distillation. The strands can then be discharged by conventional methods to form chips. Here, the formation of the generated particles begins after the polycondensation catalyst is added. As the solution is distilled away, the solubility of the product decreases, and the product precipitates as particles.

[0058] The intrinsic viscosity (intrinsic viscosity) of the polyester resin composition is preferably 0.5 to 1.5 dL / g. When the intrinsic viscosity is within this range, the physical properties of the irregularly shaped cross-section polyester fibers obtained by spinning the resin composition do not deteriorate, and the polyester resin composition or irregularly shaped cross-section polyester fibers are easy to manufacture.

[0059] <Process (III)> Next, the polyester resin composition obtained in step (II) is melt-spun to obtain irregularly shaped cross-section polyester fibers. In the manufacturing method of the present invention, it is important to supply the polyester resin composition to a spinning apparatus and perform melt spinning, and then carry out the following steps (1) to (3) in order. (1) When spinning yarn from the spindle nozzle, the spinning temperature (spindle temperature) is set to 280-300°C, and melt spinning is performed. (2) The spun yarn is cooled by blowing cooling air at 20-30°C onto it from a position 50-150 mm below the bottom of the die nozzle. (3) Wind at 2500-3500 m / min.

[0060] First, the polyester resin composition obtained in step (II) is used to form chips by drying or other treatments as necessary. These chips are then kneaded and melted using a conventional spinning apparatus, for example, in an extruder, and melt-spun by extruding them through a spinneret corresponding to the desired shape of the irregular cross-section to obtain partially oriented undrawn yarn.

[0061] In step (1), melt spinning is performed at a spinning temperature (spindle temperature) of 280 to 300°C when spinning yarn from the spindle nozzle. The spinning temperature (spindle temperature) is preferably 285 to 295°C. If the spinning temperature is too high, the resin will undergo thermal decomposition, making smooth spinning difficult, and the resulting irregularly shaped polyester fibers tend to have inferior strength and elongation. On the other hand, if the spinning temperature is too low, undissolved material tends to remain, which can easily cause yarn breakage during spinning. In addition, the resulting irregularly shaped polyester fibers tend to have low strength and elongation.

[0062] Next, in step (2), it is necessary to cool the melt-spun yarn from the die nozzle by blowing cooling air onto it at a position 50 to 150 mm from the bottom surface of the die nozzle, and more preferably at a position 90 to 130 mm from the bottom surface of the die nozzle. In the manufacturing method of the present invention, it is believed that blowing cooling air onto the spun yarn at the above range from the bottom surface of the die nozzle causes the spun yarn to crystallize appropriately, making it possible to obtain irregularly shaped cross-section polyester fibers that satisfy the degree of crystallinity defined in the present invention. In other words, if cooling air is not blown onto the spun yarn at the above position from the bottom surface of the die nozzle, it becomes difficult to obtain irregularly shaped cross-section polyester fibers that satisfy the degree of crystallinity defined in the present invention, making it impossible to spin fibers with complex irregular cross-sections, and it also becomes difficult to obtain fibers with the strength defined in the present invention.

[0063] The cooling air temperature is preferably 20-30°C, and more preferably 22-27°C. If the cooling temperature is too low, it becomes difficult to control the temperature and workability, and if it is too high, it becomes insufficient cooling, making it difficult to obtain polyester fibers with complex shapes.

[0064] After step (2), it is preferable to gather the cooled yarn and perform oiling. Alternatively, after oiling, entanglement treatment may be performed using an interlacing nozzle or the like as needed.

[0065] In the manufacturing method of the present invention, by bundling and oiling, the spinning tension is reduced, and the spinnability of the irregularly shaped cross-section polyester fiber is improved. To reduce oil film resistance, it is preferable to use an oil with a concentration of 1 to 5% by mass, more preferably 2 to 4% by mass, and to apply the oil component in an amount of 0.03 to 0.3% by mass, more preferably 0.04 to 0.2% by mass, to the entire yarn.

[0066] If the oil concentration is less than 1% by mass, or if the amount of oil component adhering to the entire yarn is less than 0.03% by mass, the yarn's ability to bundle will deteriorate, leading to frequent single-fiber breakage due to friction in subsequent processes, or the presence of loose threads in the package. On the other hand, if the oil concentration exceeds 5% by mass, or if the amount of oil component adhering to the entire yarn exceeds 0.3% by mass, the spinning tension will increase due to the resistance of the oil film, leading to frequent yarn breakage or uneven fineness in the resulting fibers. Mineral oil can be used as an oiling agent, and if necessary, oils with added antistatic agents or other additives can be used.

[0067] In step (3), the yarn that has passed through step (1) is wound at a speed of 2500 to 3500 m / min to obtain irregular cross-section polyester fibers. In particular, a winding speed of 2600 to 3300 m / min is preferred. If the winding speed is less than 2500 m / min, the obtained irregular cross-section polyester fibers will have a low degree of fiber orientation. For this reason, if a drawing process is carried out afterward, it will be necessary to draw at a high magnification, which makes it easy for fuzz and broken threads to occur and results in poor operability. Also, if the winding speed exceeds 3500 m / min, the fiber orientation and crystallization will progress too much, making it easy for fuzz and thread breakage to occur when drawing or false twisting is performed.

[0068] In step (3), it is preferable to perform further oiling before winding the yarn. Here, an oil is applied to improve the bundleability of the yarn when winding, to wind it into a good package, and to improve operability in post-processing. It is preferable to use an oil with a concentration of 5 to 18% by mass, more preferably 7 to 15% by mass, and to apply it so that the amount of oil component adhering to the entire yarn is 0.4 to 1.4% by mass, more preferably 0.7 to 1.2% by mass. Note that the amount of oil adhering is the sum of the oil applied in the oiling step after the cooling step in (2) above.

[0069] If the oil concentration is less than 5% by mass, or if the amount of oil component adhering to the entire yarn is less than 0.4% by mass, the yarn will not be sufficiently coated with oil, resulting in reduced bundleability, frequent single-fiber breakage due to friction in subsequent processes, and the presence of loose threads in the package. On the other hand, if the oil concentration exceeds 18% by mass, the dispersibility in the solvent decreases, making it difficult to uniformly adhere to the yarn, resulting in uneven adhesion and frequent yarn breakage in subsequent processes. Furthermore, if the amount of oil component adhering to the entire yarn exceeds 1.2% by mass, the amount of adhesion becomes excessive, leading to smoke generation and heater contamination in subsequent processes, thus degrading the environment.

[0070] The irregularly shaped cross-section polyester fiber of the present invention may be used as a composite fiber with other fibers. Furthermore, the form of the irregularly shaped cross-section polyester fiber of the present invention may be long fibers or short fibers, and post-processing such as crimping, false twisting, or chemical treatment may be applied as needed.

[0071] The method of false twisting is not particularly limited and can be carried out using conventionally known conditions. Pin type, friction disc type, belt type, etc., can be used as false twisting devices. The stretch ratio in false twisting is preferably 1.10 to 1.70 times, and more preferably 1.2 to 1.6 times.

[0072] The false twist count is preferably 2000 to 5000 T / M, and more preferably 2200 to 4000 T / M. The temperature of the heat treatment heater (false twist temperature) is preferably 170 to 250°C, and more preferably 180 to 245°C. The K value (T2 / T1, T2: untwist tension, T1: twist tension) is preferably 0.7 to 3.0.

[0073] Other fibers that can be used for the composite include, for example, natural fibers such as cotton, linen, and silk; regenerated fibers such as rayon; semi-synthetic fibers such as acetate; or thermoplastic fibers such as polyester fibers. Furthermore, the cross-sectional shape of the individual fibers constituting each fiber is not particularly limited, and a suitable cross-sectional shape such as chrysanthemum-shaped, circular, flat, or Y-shaped may be selected considering the texture and luster of the resulting textile product. The fineness of the individual fibers and the dyeing characteristics of the other fibers are also not particularly limited. Moreover, the irregularly shaped cross-sectional polyester fibers of the present invention may be twisted, and in this case, the direction of twisting and the number of twists are also not particularly limited, and the number of constituent yarns, the number of twists, etc., may be selected as appropriate within a range in which the texture and appearance of the desired textile product can be obtained.

[0074] Next, the woven or knitted fabric of the present invention is a woven or knitted fabric that contains at least a portion of the irregular cross-section polyester fibers of the present invention. The content of the irregular cross-section polyester fibers of the present invention in the woven or knitted fabric of the present invention is preferably 25% by mass or more, and more preferably 35% by mass or more. The woven or knitted fabrics of the present invention are not particularly limited in terms of structure or other characteristics. Examples of woven fabrics include woven, twill, satin, dobby, and double weave. Similarly, the knitted fabrics of the present invention are not particularly limited in terms of structure or other characteristics, and examples include circular knitting such as plain knit, smooth knit, rib knit, and pique, as well as warp knitting such as single tricot and half tricot.

[0075] As described above, the irregularly shaped cross-section polyester fiber of the present invention has one or more protrusions on the outer circumference of the single-fiber cross-section. Therefore, by using this irregularly shaped cross-section polyester fiber to make woven or knitted fabrics, fine gaps are formed between the fibers, resulting in woven or knitted fabrics with excellent sweat absorption and diffusion properties. Specifically, when the irregularly shaped cross-section polyester fiber of the present invention is used to make woven or knitted fabrics, the water absorption and diffusion area is 5.0 cm². 2 Preferably, it should be 6.0 cm or more. 2 It is more preferable that it be greater than or equal to 5.0 cm. 2 As a result of the above, when woven or knitted fabrics are used for clothing, if the garment gets wet due to sweat or other factors, the water absorbed into a part of the fabric spreads easily, drying quickly and thus reducing discomfort for the wearer. Details of the method for measuring the water absorption and diffusion area will be described later in the examples.

[0076] The irregularly shaped cross-section polyester fiber of the present invention is suitable for clothing applications and, due to its excellent color development and bulkiness, can also be used in interior products such as carpets and curtains, and various industrial materials. Furthermore, when used in textile products such as swimwear, sports innerwear, lingerie, foundations, and embroidered lace, the irregularly shaped cross-section polyester fiber of the present invention may be used alone or in combination with other fibers. By combining it with other fibers, textures such as gloss, coolness, crispness, and wetness can be imparted to textile products. [Examples]

[0077] The present invention will be described in detail below with reference to examples and comparative examples. However, the present invention is not limited to the following examples. The measurement or evaluation methods for each physical property are as follows: (1) Breaking strength and elongation at break The obtained irregularly shaped cross-section polyester fibers were used as samples, and according to JIS-L-1013, the strength and elongation were measured when the samples were stretched to break using Tensilon RTC-1210 (manufactured by Orientec Co., Ltd.) under conditions of a sample yarn length of 10 cm and a tensile speed of 10 cm / min. (2) Degree of crystallinity The degree of crystallinity of the irregularly shaped cross-section polyester fibers was measured by the method described above. (3) Operability The yarn breakage rate during false twisting of the obtained irregularly shaped polyester fibers was evaluated in three stages, based on the number of yarn breakages per spindle during 24 hours of continuous false twisting, as follows. ○...The number of times the thread broke was 10 or less. △··The number of times the thread broke was between 11 and 19. ×...The thread broke more than 20 times. (4) Number of protrusions The obtained irregularly shaped polyester fibers were cut perpendicular to the longitudinal direction of the fiber, and the cross-sections were observed at 100x magnification using a transmission microscope ("BH-2 UMA," manufactured by Olympus Corporation) to determine the number of protrusions. (5) Flatness of polyester fibers Using a transmission microscope ("BH-2 UMA," manufactured by Olympus Corporation), the flatness of the main part of the fiber cross-section of irregularly shaped polyester fibers was calculated using the following formula. Measurements were taken for all filaments, and the average value was used. Flatness = (Length of the longer side of the core) / (Length of the shorter side of the core) (6) Thickness ratio between the protrusion and the core Using a transmission microscope (Olympus BH-2 UMA), the thickness ratio of the core to the convex portion of the cross-section of the polyester fibers constituting the knitted fabric was calculated using the following formula. Measurements were taken for all filaments, and the average value was used. The ratio of the thickness of the protrusion to the core = (height of the protrusion) / (length of the shorter side of the core) (7) Water absorption and diffusion area A 10cm x 10cm tubular knitted fabric was prepared using irregularly shaped cross-section polyester fibers. After the tubular knitted fabric was placed horizontally, 100 μl of pure water was dropped onto the fabric from a height of 0.5 cm using a dropper. The diffusion area S (cm²) after 1 minute was measured. 2 The area was determined and used as the water absorption and diffusion area. (8) Texture evaluation (Crunchy texture) The resulting tubular knitted fabrics were evaluated based on their tactile feel according to the following criteria. ○: Excellent texture ×: Inferior in terms of texture (Dry feeling) The resulting tubular knitted fabrics were evaluated based on their tactile feel according to the following criteria. ○: Excellent dryness ×: Inferior in dryness

[0078] <Manufacturing of polyester resin compositions> A slurry of terephthalic acid (TPA) and ethylene glycol (EG) (molar ratio TPA:EG = 1.6) was continuously supplied to an esterification reactor and reacted under conditions of 250°C and 50 hPa, continuously obtaining a low-polymer polyester with an esterification reaction rate of 95%. 46.5 kg (80 parts by mass) of this low-polymer polyester was added to a polycondensation reactor, and the inside of the container was purged with nitrogen. Next, 7.3 kg (⇒ 6 parts by mass) of an EG dispersion in which the concentration of adipic acid (hereinafter abbreviated as AD), an aliphatic dicarboxylic acid having 5 to 10 carbon atoms, was adjusted to 25% by mass, and magnesium acetate, an alkaline earth metal salt of the carboxylic acid, was added at a concentration of 12.5 × 10⁻¹⁶ per mole of the acid component constituting the polyester. -4 The mixture was added in molar form, the temperature inside the polycondensation reactor was set to 270°C, and the mixture was stirred for 5 minutes. Furthermore, triethyl phosphate, a phosphate ester, was added to the polycondensation reactor at a rate of 14.5 × 10⁻¹⁶ per mole of the acid component constituting the polyester. -4 5.6 kg (⇒ 10 parts by mass) of an EG solution, adjusted so that the concentration of EG ester of 5-sodium sulfoisophthalic acid (hereinafter abbreviated as SIP), an aromatic dicarboxylic acid having a metal sulfonate group, is 35% by mass, was added, and the temperature in the polycondensation reaction vessel was set to 270°C, and the mixture was stirred for 60 minutes. Furthermore, antimony trioxide was added to the polycondensation reaction vessel as a polycondensation catalyst at a concentration of 2.0 × 10⁶ per mole of the acid component constituting the polyester. -4 Moles were added. The pressure was gradually reduced to 1.2 hPa or less after 1 hour. Under these conditions, a polycondensation reaction was carried out for 4 hours with stirring, after which the mixture was discharged by a conventional method and pelletized to obtain a polyester resin composition with an intrinsic viscosity of 0.55 dL / g.

[0079] Example 1 The obtained polyester resin composition was fed into a standard melt spinning machine, and melt spinning was performed using a spinneret designed to produce fibers with the cross-sectional shape shown in Figure 1. The spinning temperature was 285°C. Cooling air (24°C) was blown onto the melt-spun yarn from the spinneret nozzle at a position 93 mm from the bottom of the nozzle to cool it, and it was then passed through a bundling and oiling device (oil supply device) to be treated with an oil at a concentration of 4% by mass. Next, before winding the yarn, an additional 14% by mass oil was applied, and then it was wound up at a speed of 3000 m / min on a take-up roller to obtain a partially oriented undrawn yarn (irregular cross-sectional polyester fiber) with an arrow-shaped cross-section (100dtex44f). Next, the obtained irregularly shaped cross-section fibers were used as supply yarn, and false twisting was performed using a filament friction false twisting machine under the conditions of a draw ratio of 1.575, a non-contact heater temperature of 245°C, and a K value (T2 / T1, T2: untwisting tension, T1: twisting tension) of 0.84 to obtain false twisted yarn. Using only the obtained false-twisted yarn, a tubular knitting machine (manufactured by Eiko Sangyo Co., Ltd., bobbin diameter: 3.5 inches, needle count: 260N) was used to produce a plain knit fabric with 38 wales / 2.54 cm and 50 courses / 2.54 cm. The obtained tubular knitting machine was then scouring, dyeing, and water-absorbing treatment according to the following formula to obtain a tubular knitted fabric. <Scouring> 80℃×20 minutes Surfactant "Sunmol FL" (manufactured by Nikka Chemical Co., Ltd.) 1g / L <Dyeing / water absorption processing> 100℃ x 60 minutes • Cationic dye "Astrazon Blue" (manufactured by Katayama Chemical Industry Co., Ltd.) 0.5% omf • Acetic acid (48%) 0.2 cc / l Sodium acetate 0.2g / l • Polyester-based water-absorbing agent "SR-1000" (manufactured by Takamatsu Oil & Fat Co., Ltd.) 2.0% omf

[0080] Example 2 A partially oriented undrawn yarn with an arrow-shaped cross-section (irregular cross-section polyester fiber) was obtained in the same manner as in Example 1, except that the spinning temperature in step (1) was set to 295°C (100dtex48f). Next, a tubular knitting machine was obtained in the same manner as in Example 1, and then scouring, dyeing, and water absorption processing were performed in the same manner as in Example 1 to obtain a tubular knitted fabric.

[0081] Example 3 The obtained polyester resin composition was fed into a standard melt spinning machine, and melt spinning was performed using a spinneret designed so that the fiber cross-sectional shape would be as shown in Figure 4. The spinning temperature was 280°C. Cooling air (24°C) was blown onto the melt-spun yarn from the spinneret nozzle at a position 113 mm from the bottom of the nozzle to cool it, and it was passed through a bundling and oiling device (oil supply device) to be coated with an oil at a concentration of 4% by mass. Next, before winding the yarn, an additional 14% by mass oil was applied, and then it was wound on a take-up roller at a speed of 3000 m / min to obtain a partially oriented undrawn yarn with a multi-lobed cross-sectional shape (irregular cross-sectional polyester fiber) (122dtex44f). Next, a tubular knitting machine was obtained in the same manner as in Example 1, and then scouring, dyeing, and water absorption processing were performed in the same manner as in Example 1 to obtain a tubular knitted fabric.

[0082] Example 4 A partially oriented undrawn yarn with a multi-lobed cross-section (irregular cross-section polyester fiber) was obtained in the same manner as in Example 3, except that the winding speed in step (3) was set to 3300 m / min (122dtex48f). Next, a tubular knitting machine was obtained in the same manner as in Example 1, and then scouring, dyeing, and water absorption processing were performed in the same manner as in Example 1 to obtain a tubular knitted fabric.

[0083] Comparative Example 1 A partially oriented undrawn yarn with an arrow-shaped cross-section (irregular cross-section polyester fiber) was obtained in the same manner as in Example 1, except that the spinning temperature in step (1) was set to 275°C (100dtex44f). Next, a tubular knitting machine was obtained in the same manner as in Example 1, and then scouring, dyeing, and water absorption processing were performed in the same manner as in Example 1 to obtain a tubular knitted fabric.

[0084] Comparative Example 2 A partially oriented undrawn yarn with an arrow-shaped cross-section (irregular cross-section polyester fiber) was obtained in the same manner as in Example 1, except that the spinning temperature in step (1) was set to 305°C (100dtex48f). Next, a tubular knitting machine was obtained in the same manner as in Example 1, and then scouring, dyeing, and water absorption processing were performed in the same manner as in Example 1 to obtain a tubular knitted fabric.

[0085] Comparative Example 3 Except for setting the cooling air blowing position in step (2) to 30 mm from the bottom surface of the nozzle, a partially oriented undrawn yarn with an arrow-shaped cross-section (irregular cross-section polyester fiber) was obtained in the same manner as in Example 1 (122dtex44f). Next, a tubular knitting machine was obtained in the same manner as in Example 1, and then scouring, dyeing, and water absorption processing were performed in the same manner as in Example 1 to obtain a tubular knitted fabric.

[0086] Comparative Example 4 Except for setting the cooling air blowing position in step (2) to 200 mm from the bottom surface of the nozzle, a partially oriented undrawn yarn with an arrow-shaped cross-section (irregular cross-section polyester fiber) was obtained in the same manner as in Example 1 (122dtex48f). Next, a tubular knitting machine was obtained in the same manner as in Example 1, and then scouring, dyeing, and water absorption processing were performed in the same manner as in Example 1 to obtain a tubular knitted fabric.

[0087] Comparative Example 5 A partially oriented undrawn yarn with an arrow-shaped cross-section (irregular cross-section polyester fiber) was obtained in the same manner as in Example 1, except that the cooling temperature in step (2) was set to 15°C (100dtex44f). Next, a tubular knitting machine was obtained in the same manner as in Example 1, and then scouring, dyeing, and water absorption processing were performed in the same manner as in Example 1 to obtain a tubular knitted fabric.

[0088] Comparative Example 6 A partially oriented undrawn yarn with an arrow-shaped cross-section (irregular cross-section polyester fiber) was obtained in the same manner as in Example 1, except that the cooling temperature in step (2) was set to 35°C (100dtex48f). Next, a tubular knitting machine was obtained in the same manner as in Example 1, and then scouring, dyeing, and water absorption processing were performed in the same manner as in Example 1 to obtain a tubular knitted fabric.

[0089] Comparative Example 7 A partially oriented undrawn yarn with an arrow-shaped cross-section (irregular cross-section polyester fiber) was obtained in the same manner as in Example 1, except that the winding speed in step (3) was set to 1800 m / min (122dtex44f). Next, a tubular knitting machine was obtained in the same manner as in Example 1, and then scouring, dyeing, and water absorption processing were performed in the same manner as in Example 1 to obtain a tubular knitted fabric.

[0090] Comparative Example 8 A partially oriented undrawn yarn with an arrow-shaped cross-section (irregular cross-section polyester fiber) was obtained in the same manner as in Example 1, except that the winding speed in step (3) was set to 4000 m / min (122dtex48f). Next, the obtained irregularly shaped cross-section fibers were used as the supply yarn, and false twisting was performed using a filament friction false twisting machine under the conditions of a draw ratio of 1.575, a non-contact heater temperature of 245°C, and a K value (T2 / T1, T2: untwisting tension, T1: twisting tension) of 0.84. However, the resulting false twisted yarn had a large number of fluffs and breaks, making it insufficient for practical use.

[0091] The results are shown in Tables 1 and 2.

[0092] [Table 1]

[0093] [Table 2]

[0094] As is clear from Tables 1 and 2, Examples 1-4 exhibited excellent operability because the fiber strength, elongation, and crystallinity were within the specified range. Furthermore, the woven and knitted fabrics using the obtained irregular cross-section polyester fibers exhibited excellent absorbency and diffusion, providing a cool and refreshing feel (crisp and dry). In addition, the resulting tubular knitted fabrics were dyed to the desired color, demonstrating that the irregular cross-section polyester fibers of the present invention exhibited excellent dyeability with cationic dyes under normal pressure conditions. [Explanation of symbols]

[0095] 1: Core 2: Convex part 3: Long side 4: Short side 5: Height of the protrusion 6: Inscribed circle of an irregularly shaped cross-section 7: Circumscribed circle of an irregularly shaped cross-section

Claims

1. A polyester fiber comprising a polyester resin containing, when the total amount of all acid components constituting the polyester is 100 mol%, 80 mol% or more of terephthalic acid, 0.5 to 5 mol% of aromatic dicarboxylic acid having a metal sulfonate group and 2 to 18 mol% of aliphatic dicarboxylic acid having 5 to 10 carbon atoms, and when the total amount of all glycol components is 100 mol%, 80 mol% or more of ethylene glycol, characterized in that it has an irregular cross-sectional shape having one or more protrusions on the outer circumference in a cross section perpendicular to the longitudinal direction of the yarn, and satisfies all of the following characteristics (a) to (c). (a) containing alkaline earth metal compounds and phosphorus compounds (b) Fiber strength of 1.4 cN / dtex or higher (c) Crystallinity obtained by the method described below is 12-14% Crystallinity Using a differential scanning calorimeter, 8.5 mg of the fiber sample is heated from 25°C to 280°C at a rate of 20°C / min, and the values ​​obtained (ΔHm, ΔHc) are calculated using the following formula. Crystallinity = {(ΔHm - ΔHc)} / 140.2} × 100 (%) (ΔHm represents the heat at the melting point, and ΔHc represents the heat at which crystallization occurs with heating.)

2. A textile product comprising at least a portion of the irregularly shaped cross-section polyester fiber described in claim 1.

3. A method for producing a deformed cross-section polyester fiber according to claim 1, wherein the alkaline earth metal compound is 5 × 10¹⁶ per mole of the acid component constituting the polyester. －４ ~70 x 10 －４ Moles, phosphorus compounds: 1 x 10⁻¹⁶ per mole of the acid component constituting the polyester －４ ~100 x 10 －４ A method for producing irregularly shaped cross-section polyester fibers, characterized by using a mol-containing polyester resin and performing the following steps in order. (1) When spinning yarn from the spindle nozzle, the spinning temperature (spindle temperature) is set to 280-300°C, and melt spinning is performed. (2) The spun yarn is cooled by blowing cooling air at 20 to 30°C onto it from a position 50 to 150 mm below the bottom surface of the die nozzle. (3) Wind at 2500-3500 m / min.

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