KR20110032236A - Polyamide filaments with modified cross-section and preparing method thereof - Google Patents

Abstract

PURPOSE: A method for fabricating polyamide filaments with modified cross-section is provided to ensure excellent absorption and deep color. CONSTITUTION: A polyamide filaments contains basic dye polyamide copolymers with sulfonic acid group. The basic dye polyamide copolymer contains 90-95 weight% of upsilon-caprolactam, 1-5 weight% of isophthalic acid, and 0.1-5 weight% of methaxylenediamine. A method for fabricating polyamide filaments with modified cross-section comprises: a step of preparing a dye polyamide chip containing sulfonic acid; and a step of spinning yarn of dumbbell-shaped modified cross-section.

Description

Polyamide based cross section fiber and its manufacturing method {Polyamide Filaments with modified cross-section and Preparing method

The present invention relates to a polyamide-based cross-sectional fiber and a method for manufacturing the same, and more particularly, to a polyamide-based hetero-cross-section fiber excellent in color development by basic dyes, excellent in water absorption, uprightness and deep colorability, and a method for producing the same. will be.

Polyamide fibers have been very useful in many fields because of their superior strength, abrasion resistance, and dyeability compared to other synthetic fibers.

However, in recent years, the demand characteristics in each field are gradually diversified, and the demand for special functionality and excellence is increasing, and the demand for more improved characteristics is also gradually increasing in general medical use, and conventional polyamide fibers alone satisfy these demands. I can't let that happen.

In general, polyamide fibers have excellent dyeing properties for acid dyes, but they do not have good dyeing properties for basic dyes, so they can meet consumer's preference for products requiring diverse and colorful colors such as pattern carpets, textiles, and knitwear. There have been many limitations in expressing color. This problem is the same in medical fibers. In particular, many proposals have been made in the related art for improving color development of polyamide-based fibers.

First, a method of introducing mono or dicarboxybenzene having a sulfonate group into polyamide is described in Japanese Patent Publications Nos. 37-14646 and 37-14647, and a polyamide of di (sodium sulfonate) naphthalene-2-carboxylic acid compound is used. Japanese Patent Publication No. 44-1236 discloses a method of introducing the polymer into the polymer, but the proposed method prevents an increase in the degree of polymerization by blocking the polymer end excessively during the polymerization of ε-caprolactam. There is a problem that the physical and mechanical properties of the deterioration.

Next, a method of introducing poly (alkylene ether derivatives) having sulfonic acid groups into polyamides is disclosed in Japanese Patent Laid-Open Nos. 46-41016 to 41019, which method can produce fibers having excellent affinity for basic dyes. However, due to the fusion of the yarn during the spinning process in the spinning process, there is a problem that the generation of trimming and workability is significantly reduced and the washing fastness of the product is lowered.

In addition, a method of introducing sulfonated polystyrene into polyamide is disclosed in Japanese Patent Publication No. 43-24229, etc., where the sulfonated polystyrene is poorly compatible with polyamide, which causes a lot of trimming in the sacrificial process. There is a problem, and there is a fatal defect that is eluted when immersed in warm hot water.

Finally, in order to obtain the desired molecular weight (i.e. sufficient degree of polymerization) together with the isophthalic acid component containing the metal sulfonic acid group (e.g., the 5-potassium sulfo isophthalic acid component), the same mole number of diamine is added and copolymerized. Japanese Patent Application Publication Nos. 37-14645 and 37-14616, and U.S. Patent No. 3,039,990, but the polyamide copolymers obtained by this method have basic dyes because they have the same number of amino groups and carboxyl groups at the terminals. In addition, the affinity for acid dyes is also increased. Therefore, when it is dyed in an acid-base dye mixing bath with the general polyamide, there is a problem that does not show a vivid color development, but also contaminated color development.

One problem to be solved by the present invention is to provide a polyamide-based cross-sectional fiber having excellent color development as well as excellent absorbency, uprightness, deep color.

Another problem to be solved by the present invention is to provide a method for producing the polyamide release cross-section fiber, a method that can be produced uniformly as well as good operability.

Another problem to be solved by the present invention is to provide a dibasic polyamide-based fiber showing excellent color development.

One aspect of the present invention for achieving the above object relates to a polyamide-based heteromorphic cross-sectional fiber comprising a basic dye salt-containing polyamide copolymer comprising a sulfonic acid group, having a dumbbell-shaped cross section.

The basic dye salt-containing polyamide copolymer including the sulfonic acid group may be a polyamide copolymerized with a dicarboxybenzenesulfonate compound represented by Formula 1 and a diamine compound represented by Formula 2 below.

[Formula 1]

Where

Z is selected from the group consisting of Na, K, and Li,

R is an alkyl group having 1 to 3 carbon atoms,

m is 0 or 1,

R 'is hydrogen or an alkyl group having 1 to 3 carbon atoms.

 [Formula 2]

H ₂ NR-NH ₂

Wherein R is an alkyl group having 2 to 12 carbon atoms or a phenyl group.

Another aspect of the present invention for achieving the above object is a method for producing a polyamide-based heteromorphic cross-sectional fiber, the method comprises the step of preparing a basic dye salt-containing polyamide chip containing a sulfonic acid group and a dumbbell-shaped cross-section It relates to a method for producing a polyamide-based release cross-section fiber comprising the step of spinning a yarn.

In the spinning step, it is preferable to use the shape of the nozzle of the release cross-section spinneret dumbbell type, it is preferable to spin at a high speed of 4,000m / min or more spinning speed, but is not limited thereto.

Another aspect of the present invention for achieving the above object is a chlorinated polyamide-based fiber prepared by weaving or knitting together a polyamide-based release cross-section fiber and a polyamide fiber comprising the basic dye salt-type polyamide copolymer Related to.

Polyamide-based heteromorphic fiber according to embodiments of the present invention comprises a basic dye salt-containing polyamide copolymer comprising a sulfonic acid group that is selectively dyed in the cationic dye, and has a heteromorphic cross-section of the dumbbell-like to the basic dye It shows good color development, and has good absorbency, uprightness and deep colorability. In addition, it is possible to produce a fiber having good spinning workability and cross-sectional uniformity without generating trimming or bending in melt spinning through the dumbbell-shaped release cross-section spinneret. In addition, the polyamide-based release cross-section fibers according to embodiments of the present invention can express the dichroism by dichroism by weaving or knitting together with the general polyamide fibers.

Hereinafter, with reference to the accompanying drawings will be described in more detail with respect to the present invention.

One aspect according to one embodiment of the present invention relates to a polyamide-based heteromorphic cross-section fiber comprising a basic dye salt-containing polyamide copolymer comprising a sulfonic acid group and having a dumbbell-shaped cross section.

The cross-section of the dumbbell shape means that, as illustrated in FIG. 1, two circular or elliptical shapes on both left and right sides are connected by intermediate bars.

Polyamide-based release cross-sectional fibers according to embodiments of the present invention includes a basic dye salt-containing polyamide copolymer containing a sulfonic acid group to improve color development.

Normally, polyamide fibers are not dyed in basic dyes but dyed only in acid dyes because the acid dyes chemically bond to the amine end groups. Therefore, in order to dye the basic dye, a method of replacing an amine end group with a sulfonic acid group having a basic dye salting type including a sulfonic acid group is required. To this end, a method of copolymerizing by adding a compound containing a sulfonic acid group in a polymerization step may be used.

The basic dye salt-containing polyamide copolymer including the sulfonic acid group may be a polyamide copolymerized with a dicarboxybenzenesulfonate compound represented by Formula 1 and a diamine compound represented by Formula 2 below.

[Formula 1]

In the formula, Z is selected from the group consisting of Na, K, and Li, R is an alkyl group having 1 to 3 carbon atoms, m is 0 or 1, R 'is hydrogen or an alkyl group having 1 to 3 carbon atoms.

 [Formula 2]

H ₂ NR-NH ₂

Wherein R is an alkyl group having 2 to 12 carbon atoms or a phenyl group.

According to embodiments of the present invention, a yarn is prepared using a basic dye salt-type polyamide copolymer including a sulfonic acid group that is selectively dyed to a cationic dye, and after weaving and knitting with general polyamide, an acid dye and a cationic When dyeing proceeds in the same bath of the dye, the dichroism is expressed by selective dyeing.

That is, the dichroic polyamide-based heteromorphic cross-sectional fiber according to the embodiments of the present invention exhibits the dichroism by dichroism and simultaneously shows the absorbency, uprightness, and deep color function by the dumbbell-shaped heteromorphic cross section. Can be provided.

Specifically, the erectivity is related to the repulsive force of the fiber, the fiber having a dumbbell-shaped cross-section according to the embodiments of the present invention form a form without easily lying down or falling down when producing a towel (pile), such as towels, carpet yarns, etc. It can provide maintainable uprightness, and the fibers with hetero-sections have the bends and gaps of the filaments themselves, compared to the general circular cross-sections, so that when they come together to form a fiber aggregate product, they form finer and more capillaries. In the case of synthetic fibers, the absorption of moisture is mostly made of the water transition by the capillary bar, the fiber having a dumbbell-shaped cross-section according to the embodiments of the present invention has excellent absorption through water transfer by the heteromorphic section capillary Can be expressed. In addition, after weaving and knitting fibers prepared using a basic dye salt-type polyamide copolymer containing sulfonic acid groups which are selectively dyed into cationic dyes and general polyamide fibers, copper baths of acid dyes and cationic dyes 염색) If the dye proceeds in the dichroic (선택 色 性) by the selective dyeing, due to the heterogeneous cross-section has a deep color.

The method for producing a polyamide-based release cross-section fiber according to embodiments of the present invention includes preparing a basic dye salted polyamide chip including a sulfonic acid group and spinning a yarn having a dumbbell-shaped release cross section. .

In the present invention, the basic dye salt-containing polyamide copolymer containing a sulfonic acid group may be exemplified by the polyamide 6 copolymer mainly containing an ε-caprolactam and an aromatic compound (dicarboxybenzenesulfonate) containing a sulfonic acid group. In preparing such a polyamide 6 copolymer, the amount of the aromatic compound containing a sulfonic acid group is applied to 0.3 to 5.0 parts by weight based on ε-caprolactam. This is because if the content is less than 0.3 part by weight, the affinity for the basic dye is not sufficient, and if the content is more than 5.0 parts by weight, the water absorbency is increased.

Examples of the dicarboxybenzenesulfonate compound include 2,5- and 3,5-dicarboxybenzenesulphonic acid, 2,5- and 3,5-dicarboxyethylbenzenesulfonic acid, 2,5- and 3,5- Sulfonate salt compounds of sodium, potassium, and lithium, such as dicarboxypropylbenzenesulfonic acid, or 2,5- and 3,5-dimethoxycarboxybenzenesulfonate, 2,5- and 3,5-dimethoxycarboxyethyl Sulfonate salt compounds of sodium, potassium, and lithium, such as benzenesulfonate, 2,5- and 3,5-dimethoxycarboxypropylpropylbenzenesulfonate, 2,5- and 3,5-diethoxycarboxyl ethylbenzene sulfone Sulfonate salts of sodium, potassium, and lithium, such as nates, 2,5- and 3,5-diethoxycarboxypropylbenzenesulfonate, 2,5- and 3,5-dihydroxycarboxyethylbenzenesulfonate, And sulfonate salt compounds of sodium, potassium, and lithium, such as 2,5- and 3,5-dihydroxycarboxypropyl benzenesulfonate.

In embodiments of the present invention, the amount of the diamine compound used to increase the degree of polymerization of the polyamide 6 copolymer is equal to or less than the same mole% of the compound dose containing the sulfonic acid group. If it is added to the polymerization at a mole% more than the sulfonate compound, the resistance to the acid dye is weakened, because it may be stained and contaminated not only basic but also acid dye.

Examples of the diamine compound include ethylenediamine, tetramethylenediamine, hexamethylenediamine, octamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, paraphenylenediamine, metaphenylenediamine, paraxylenediamine , Metaxylenediamine, metaxylenediamine, and the like.

The amine end group content of the polyamide copolymer of the present invention is preferably 30 meq / kg or less. When the concentration of the amine end group exceeds 30 meq / kg, not only the affinity for the basic dye is high but also the acid dyes. This is because dyeing unevenness and contamination are intensified.

In one embodiment of the present invention, the basic dye salt-containing polyamide copolymer containing a sulfonic acid group is 90 to 95% by weight of ε-caprolactam, 1 to 5% by weight of 5- (sodiumsulfo) isophthalic acid, metaxylenediamine It may be made of 0.1 to 5% by weight.

In addition, in the embodiments of the present invention, a biscaprolactam compound, which is a third component, may be added in the polycondensation step of the polyamide or the spinning step of the fiber for the purpose of adjusting the amine end group concentration, and by adjusting the addition amount thereof. The amine end group concentration can be arbitrarily adjusted. The amount of the biscarpolactam compound added is preferably 0.2 to 5.0 parts by weight.

Examples of the biscaprolactam compound include terephthaloyl biscaprolactam, isophthaloyl biscaprolactam, carbonyl biscaprolactam and mixtures thereof.

Polyamide-based release cross-sectional fibers according to embodiments of the present invention to produce a composite functional fiber that exhibits the absorbent, upright and deep color at the same time, as shown in Figure 1 by using a dumbbell-shaped cross section excellent functional fiber Can provide. Such a cross-sectional shape of the dumbbell-shaped spinneret can be obtained by spinning using the shape of the nozzle of the heterospindle spinneret, or a reverse shape of the spinneret, for example, if the nozzle shape of the spinneret as shown in FIG. As you pass through it, you can get closer to the dumbbell.

In the method for producing a polyamide-based release cross-section fiber according to embodiments of the present invention, the spinning step is made of melt spinning, it is preferable that the spinning speed is spinning at a high speed of 4,000m / min or more. This is because a certain level of spinning speed is required in order to orient the filament to express proper properties such as strength, dyeability, shrinkage rate, etc., which is advantageous in terms of productivity, but is not limited thereto.

The method for producing a polyamide-based release cross-section fiber according to an embodiment of the present invention may further include delayed cooling by passing the obtained release cross-section filament through a delay cooling unit directly under the release cross-section spinneret.

In the delay cooling step, the delayed cross-section filament formed by the high-speed spinning of the basic dye salt-containing polyamide copolymer including the sulfonic acid group in a nozzle having a shape of a release cross section is 5 to 80 mm in height directly under the release cross-section spinneret. The cooling is delayed by passing through the cooling section.

If the height of the delayed cooling portion for delayed cooling the release cross-section filament is less than 5 mm, the delayed cooling portion is less than that the delayed cooling effect of the release cross-section filament is insufficient, and if the height of the delayed cooling portion for delayed cooling the release cross-section filament exceeds 80 mm Deformation of the cross-section filament formed in the shape of the cross-section dumbbell may occur. Thus, by controlling the height of the delay cooling part directly under the spinneret, the delayed-cooled release cross-section filament is forcibly cooled by cold wind of constant wind speed.

Method for producing a polyamide-based release cross-section fiber according to embodiments of the present invention is to control the distance between the delayed cooled release cross-section filament and the cold air blowout surface to 2 ~ 30 mm to form a cross-sectional undrawn yarn by cooling and solidification It may further comprise a step.

Specifically, while forcedly cooling the release cross-section filament delayed cooling in the retardation cooling unit directly below the release cross-section spinneret with cold air, the distance between the release cross-section filament to be cooled and the cold air extraction surface is controlled to 2 ~ 30 mm Passing through the cross-section filament is cooled and solidified by cold wind of a constant wind speed. When cooling the release cross-section filament, if the distance between the cold air extraction surface of the forced cooling section and the release cross-section filament is controlled to be less than 2 mm, it may adversely affect the following stretching process due to the influence of excessive cold wind in the release cross-section filament. If the distance between the cold air extraction surface and the release cross-section filament is greater than 30 mm, the distance between the cold wind extraction surface and the release cross-section filament is excessive, and the forced cooling effect is insufficient.

The basic cross-linked polyamide-based release cross-section fibers of the present invention may be formed by stretching the cross-section undrawn yarn forcedly cooled by the cold air.

In addition, the method for producing a polyamide-based release cross-section fiber according to embodiments of the present invention may further include the step of stretching the release cross-section non-drawn yarn to form a release cross-section drawn yarn.

The drawn cross-section unstretched yarn forcedly cooled as described above is drawn by a plurality of drawn rollers having different traveling speeds or other known drawing techniques to form a cross-section drawn yarn, and the release cross-sectional drawn yarn is wound on a roll to form polyamide. The system release cross section fiber can be manufactured.

In addition, the method for producing a polyamide-based release cross-section fiber according to embodiments of the present invention may further include coating an emulsion on the surface of the release cross-section yarn. This is to protect the surface of the modified cross-section stretched yarn constructed as described above and to improve the feel.

Specifically, by coating the emulsion by a known method such as a metered lubrication method or a roller lubrication method on the surface of the release cross-section yarn, it is possible to provide a release cross-section fiber further improved quality and added value.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the following examples are intended to illustrate the present invention, and embodiments according to the present invention may be modified in various forms, and are defined in the appended claims. It is not intended to limit the scope of protection defined by this.

Example 1

A copolymer chip made of 95% sulfuric acid relative viscosity of 2.5 by drying a basic dye salt-containing polyamide copolymer chip containing sulfonic acid group (amine terminal group content of 20 to 25 meq / kg, sulfonic acid group concentration of 0.5 to 1.5 mol%) Was melted at 240 to 250 ° C and a fiber having a fineness of 75D was produced at a spinning speed of 5,000 m / min by a direct spinning method through a non-spin cross-section spinneret having a nozzle-shaped cross section as shown in FIG. The scanning electron microscope (Scanning Electron Microscope, SEM) photograph taken is shown in FIG.

Comparative Example 1

Fibers were prepared in the same manner as in Example 1 except that spinnerets having a general nozzle having a circular cross section were used.

Comparative Example 2

Using a general polyamide 6 chip (melting point 220 ° C., glass transition temperature 50 ° C.), fibers of fineness 75D were produced at a spinning speed of 5,000 m / min by direct spinning through the release cross-section spinneret of FIG. 2.

Comparative Example 3

A fiber was prepared in the same manner as in Comparative Example 2 except that a spinneret having a general nozzle having a circular cross section was used.

Experimental Example 1-Absorbency Evaluation

For the fibers prepared in Example 1 and Comparative Examples 1 to 3 are shown in Table 1 by weight percent of the sample weight increased after absorption relative to the original sample weight for the same time.

Experimental Example 2-Evaluation of Dryness

Table 1 shows the weight of the sample after drying in relation to the weight of the sample sufficiently absorbed for the same time with respect to the fibers prepared in Example 1 and Comparative Examples 1 to 3 in weight percent.

Experimental Example 3-Evaluation of deep color, uprightness and occurrence

After weaving a plain weave of warp density 15,000 本 and weft density 60 本 / inch using the fibers prepared in Examples 1 and Comparative Examples 1 to 3, a colorimeter (Model: Color View, manufacturer: BYK Gardner (Germany)) The deep color was evaluated by using, and the erectivity was evaluated by applying a certain weight using a certain weight to recover the color. The color development was not contaminated with an acid dye, but visually evaluated by the basic dye. Table 1 shows.

Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Absorbency (%) ◎ X ◎ X Dryability (%) ◎ X ◎ X Deep color ◎ △ ○ X Uprightness ◎ X ◎ X Color development ◎ ◎ X X

* ◎: Very good, ○: Good, △: Normal, X: Bad

As shown in Table 1, in the case of using a basic dye salt-containing polyamide copolymer containing a sulfonic acid group, and using a cross-section spinneret having a dumbbell-shaped nozzle shape (Example 1), absorbency and dryness At the same time, it can be confirmed that all of the deep color, uprightness, and color development are good. However, on the other hand, when the general polyamide chip is used (Comparative Examples 2 and 3), it can be confirmed that the color development is not good, and when the spinneret having a general circular nozzle shape is used (Comparative Examples 1 and 3), It can be seen that the composition, color depth and uprightness are all poor.

That is, from the results of the experimental examples for the above Examples and Comparative Examples, using a basic dye salt-containing polyamide copolymer containing a sulfonic acid group as in the present invention, and using a cross-section spinneret having a dumbbell-shaped nozzle shape It can be seen that the prepared fiber has excellent colorability to basic dyes, but also excellent water absorption, dryness, deep colorability, and erectivity.

Although the present invention has been described in detail with reference to preferred embodiments of the present invention, these are merely exemplary, and those skilled in the art to which the present invention pertains have various modifications and equivalents therefrom. It will be appreciated that embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

1 is a schematic view of a cross section of a polyamide-based heteromorphic cross-section fiber produced according to the present invention.

Figure 2 is a cross-sectional view of the nozzle shape of the release cross-section spinneret applied to the spinning step of the polyamide-based release cross-section fibers of one embodiment of the present invention.

1.3 = A / B = 10,

2. 3 = C / D = 10,

3. 0.1 = E / B = 0.2

Figure 3 is a scanning micrograph (SEM) of the polyamide-based heteromorphic cross-section fiber prepared according to one embodiment of the present invention.

Claims (14)

A polyamide-based heteromorphic cross-section fiber comprising a basic dye salt-containing polyamide copolymer comprising a sulfonic acid group and having a dumbbell-shaped cross section. According to claim 1, wherein the basic dye salt-containing polyamide copolymer containing a sulfonic acid group is characterized in that the polyamide is copolymerized with a dicarboxybenzene sulfonate compound represented by the formula (1) and a diamine compound represented by the formula (2) Polyamide-based release cross section fiber. [Formula 1]

Where Z is selected from the group consisting of Na, K, and Li, R is an alkyl group having 1 to 3 carbon atoms, m is 0 or 1, R 'is hydrogen or an alkyl group having 1 to 3 carbon atoms.  [Formula 2] H ₂ NR-NH ₂ Wherein R is an alkyl group having 2 to 12 carbon atoms or a phenyl group. According to claim 1, wherein the basic dye salt-containing polyamide copolymer containing a sulfonic acid group is 90 to 95% by weight of ε-caprolactam, 1 to 5% by weight of 5- (sodiumsulfo) isophthalic acid, 0.1 to metamethylenediamine Polyamide-based release cross-section fibers, characterized in that consisting of 5% by weight. According to claim 1, wherein the basic dye salt-containing polyamide copolymer containing a sulfonic acid group polyamide-based hetero-cross-section fiber, characterized in that the polyamide amine end group content is 30 meq / kg or less. In the method for producing a polyamide-based release cross-section fiber, The method comprises the steps of preparing a basic dye salt-containing polyamide chip containing a sulfonic acid group and spinning a yarn having a dumbbell-shaped release cross section. According to claim 5, wherein the preparation step of the basic dye salt-containing polyamide chip containing a sulfonic acid group is added to the dicarboxybenzenesulfonate compound represented by the formula (1) to 0.3 to 5.0 parts by weight relative to 100 parts by weight of ε-caprolactam The polyamide-based release cross-sectional fiber manufacturing method, characterized in that by the polycondensation step of adding a diamine compound represented by the formula (2) to the same mole% or less of the amount of the dicarboxybenzenesulfonate compound. [Formula 1]

Where Z is selected from the group consisting of Na, K, and Li, R is an alkyl group having 1 to 3 carbon atoms, m is 0 or 1, R 'is hydrogen or an alkyl group having 1 to 3 carbon atoms. [Formula 2] H ₂ NR-NH ₂ Wherein R is an alkyl group having 2 to 12 carbon atoms or a phenyl group. The method of claim 5, wherein the spinning step is a method for producing a polyamide-based heterosection cross-sectional fiber, characterized in that the nozzle shape of the release cross-section spinneret is used in the form of a dumbbell or a reverse base. The method of claim 5, wherein the spinning step is a method for producing a polyamide-based release cross-section fiber, characterized in that the spinning at a high speed of at least 4,000m / min. The polyamide of claim 6, wherein the chip has a polyamide amine end group content of 30 meq / Kg or less, and 0.2 to 5.0 parts by weight of the biscaprolactam compound is added to the polycondensation step of preparing the chip. Method for producing a heteromorphic cross-sectional fiber. 10. The method according to claim 9, wherein the biscaprolactam compound is added in the spinning step. 6. The method of claim 5, wherein the method further comprises the step of delayed cooling the release cross-section filament obtained in the spinning step by passing through the delayed cooling unit directly under the release cross-section spinneret of polyamide-based Manufacturing method. 12. The method of claim 11, wherein the method further comprises controlling the distance between the delayed cooled release cross-section filament and the cold air blow-out surface to 2 to 30 mm and cooling to solidify to form a release cross-section non-drawn yarn. Method for producing a polyamide-based release cross-section fiber. 13. The method according to claim 12, wherein the method further comprises the step of stretching the release cross-section non-drawn yarn to form a release cross-section drawn yarn. A dibasic polyhydride prepared by weaving or knitting a polyamide-based hetero sectional fiber and a polyamide fiber together comprising a basic dye salt-containing polyamide copolymer comprising a sulfonic acid group according to any one of claims 1 to 13. Amide-based fiber.

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