JPWO2018174106A1 - Polyamide fiber with excellent moisture absorption / release properties - Google Patents

Abstract

An object of the present invention is to provide a comfortable garment free from stuffiness using a polyamide fiber having a high moisture absorption / desorption rate. The polyamide fiber of the present invention is a polyamide fiber containing 3 to 15 wt% of polyamide and polyvinylpyrrolidone, and wherein the polyamide satisfies the following characteristics: (1) the molecular weight distribution has two peaks, (2) the ratio IL / IH of the peak intensity (IL) on the low molecular weight side to the peak intensity (IH) on the high molecular weight side in the molecular weight distribution is 0.02 to 0.10; It is.

Description

  TECHNICAL FIELD The present invention relates to a polyamide fiber having excellent moisture absorption / desorption properties, particularly a high moisture absorption / desorption rate.

  Synthetic fibers made of thermoplastic resins such as polyamides and polyesters are widely used in clothing and industrial applications because of their excellent strength, chemical resistance and heat resistance.

  In particular, polyamide fibers have excellent moisture absorption in addition to their unique softness, high tensile strength, coloring properties during dyeing, and high heat resistance, and are widely used in applications such as innerwear and sportswear. . However, compared to natural fibers such as cotton, polyamide fibers are not sufficiently hygroscopic and have problems such as stuffiness and stickiness, and are said to be inferior to natural fibers in terms of comfort, and are stuffy and sticky. There has been a history of proposals to respond to the demand for synthetic fibers that exhibit excellent moisture absorption and desorption properties for preventing odor and have comfort similar to natural fibers.

  For example, the method of adding a hydrophilic compound to a polyamide fiber has been most often studied. Patent Document 1 proposes a method of blending polyvinylpyrrolidone as a hydrophilic polymer with polyamide and spinning the polyamide fiber with a specific production method, thereby producing a polyamide fiber with improved moisture absorption performance with high productivity.

  Patent Document 2 proposes a polyamide fiber having a small yellowness by containing polyvinylpyrrolidone and by containing a certain amount of pyrrolidone. With this fiber, a fabric excellent in drying speed can be realized.

Japanese Patent Application Laid-Open No. 50-148626 Japanese Patent Application Laid-Open No. Hei 9-188917

  In the prior art, a certain level of moisture absorption / desorption properties has been obtained, and its effects have been applied to general clothing mainly for innerwear. In addition, clothing that spreads quickly when sweating is realized. However, with the change of the times, the demands have become more sophisticated, and it is not enough to simply have a high moisture absorption and desorption property and a high drying rate, and there is a strong demand to quickly eliminate the discomfort caused by the rise in humidity before sweating. is there. In particular, there has been a strong demand for a responsiveness to immediately absorb and diffuse the stuffiness generated during exercise, that is, a high moisture absorption and desorption rate. Conventionally, development from this viewpoint has not been performed, and moisture diffusion and moisture absorption have been treated as different things. Therefore, in fact, fibers that satisfy the moisture absorption and desorption rate have not been provided.

The present invention has the following constitution for the purpose of providing a polyamide fiber having a high moisture absorption / desorption rate in order to meet the above-mentioned high demands.
(1) A polyamide fiber containing polyamide and 3 to 15 wt% of polyvinylpyrrolidone, wherein the polyamide satisfies the following characteristics (a) and (b):
(A) the molecular weight distribution has two peaks, and the molecular weight of the low molecular weight side peak is 1000 to 2500;
(B) the ratio _I L / _{I H} of the low molecular weight side of the peak intensities of the molecular weight distribution _{(I L)} and high molecular weight side of the peak intensity _{(I H)} is 0.02 to 0.10.
(2) The polyamide fiber according to (1), wherein the average irregularity of the multifilament is from 1.1 to 4.
(3) The polyamide fiber according to (2), wherein the cross-sectional shape of at least one filament of the multifilament is a multilobal cross-section including three or more convex portions and three or more concave portions.
(4) A fiber product comprising at least a part of the polyamide fiber according to any one of (1) to (3).

  According to the present invention, it is possible to provide a polyamide fiber having an unprecedented high moisture absorption / release rate.

FIG. 1 illustrates a method for determining the degree of irregularity according to the present invention. FIG. 2 illustrates a method for determining the number of cross-sectional irregularities according to the present invention and a cross-sectional shape of Example 16. FIG. 3 illustrates a cross-sectional shape of a seventeenth embodiment of the present invention.

The polyamide fiber of the present invention contains 3 to 15% by weight of polyvinylpyrrolidone (hereinafter, may be abbreviated as PVP) and a polyamide.
By setting the content of polyvinylpyrrolidone to 3% by weight or more, the potential for moisture absorption and desorption increases, and by setting the content to 15% by weight or less, discomfort such as stickiness can be suppressed. The potential for moisture absorption and desorption is determined by the difference between the moisture absorption when left for 24 hours in an environment of 30 ° C. × 90% RH (relative humidity) and the moisture absorption when left for 24 hours in an environment of 20 ° C. × 65% RH. It can be expressed as a difference and is denoted by ΔMR. If PVP is 3 wt% or more, this ΔMR becomes a good value. PVP can be contained in polyamide fiber by a known method, and as described in Patent Document 2, it is a preferable example to prepare and knead PVP into polyamide. A more preferred range for the content of PVP is 3.5-15 wt%, most preferably a range of 4-15 wt%.

  The polyamide of the present invention is not particularly limited. For example, nylon 6, nylon 66, nylon 46, nylon 9, nylon 610, nylon 11, nylon 12, nylon 612, or the like, or an amide-forming functional group. And copolymerized polyamides containing copolymerized components such as laurolactam, sebacic acid, terephthalic acid, isophthalic acid, and 5-sodium sulfoisophthalic acid. Polyamides include, in addition to polyvinylpyrrolidone, various additives such as matting agents, flame retardants, antioxidants, ultraviolet absorbers, infrared absorbers, crystal nucleating agents, optical brighteners, antistatic agents, carbon And the like may be copolymerized or mixed as necessary. Addition of about 10% by weight does not greatly affect the moisture absorption performance.

Polyamide fibers of the present invention has a molecular weight distribution has two peaks, the peak on the low molecular weight side is a molecular weight of 1000 to 2500, and the peak of the peak strength of the low molecular weight side (I _L) high molecular weight side It is necessary that the ratio I _L / I _H of the intensity (I _H ) is 0.02 to 0.10. It has been discovered that when the molecular weight distribution has a peak at 1000 to 2500, PVP works effectively in the fiber and the rate of moisture absorption and desorption increases. Since PVP is easily dissolved in water, the entanglement between PVP and polyamide has been conventionally strengthened, thereby suppressing the dissolution of PVP into water. Although this entanglement is strong, it is considered that the rate of moisture absorption and desorption is not increased. However, if the entanglement is weak, PVP is dissolved in water, and the moisture absorption performance itself is reduced, suggesting a so-called trade-off relationship. In order to eliminate this relationship, the present inventors have made intensive studies and have arrived at the present invention.

In other words, it is presumed that the function of the amino group of the low molecular weight substance efficiently supplies water to PVP, and improves the moisture absorption rate even in a state of strong entanglement. Accordingly, the low molecular weight side peak is listed as having a molecular weight of 1,000 to 2,500, and if the molecular weight is less than 1,000, elution to water occurs to inhibit the entanglement of PVP and polyamide, and the moisture absorption / release property does not increase, When the molecular weight is larger than 2500, PVP cannot work effectively, so that the moisture absorption rate does not increase. More preferred low molecular weight peaks have a molecular weight of 1200-2200, most preferably 1400-2000. Further, if the ratio _I L / _{I H} of the peak strength of the low molecular weight side _{(I L)} and high molecular weight side of the peak intensity _{(I H)} is at 0.02-0.10 and dissolution inhibition in water absorbing Wet rate is compatible. If it is less than 0.02, the effect of improving the moisture absorption / desorption rate is extremely small, and if it is more than 0.10, the dissolution into water cannot be suppressed. A more preferred ratio of the peak intensities is in the range of 0.03 to 0.10.

  In order to develop a peak on the low molecular weight side, a state in which a low molecular weight polyamide is added is preferable. As described above, various main polyamides forming a peak on the high molecular weight side can be applied, but the polyamide on the low molecular weight side may be the same as or different from the main polyamide. Finally, it is sufficient that the molecular weight distribution has two peaks at the fiber stage. It is conceivable that the molecular weight of the low-molecular-weight polyamide added before spinning is shifted by spinning. For example, when held in a molten state for a long time, the molecular weight increases, and when water is given in the molten state, the molecular weight decreases. A desired fiber is manufactured through adjustments under these yarn forming conditions. The simplest method is to offset as much as possible the molecular weight corresponding to the increased amount in the molten state with water so that the molecular weight distribution of the prepared polyamide and the molecular weight of the polyamide as the fiber are not changed as much as possible. According to this method, the polyamide fiber of the present invention can be easily produced by adding a desired low molecular weight polyamide to the main polyamide before spinning.

  The cross-sectional shape of the polyamide fiber of the present invention may be any of a general round cross-section and a modified cross-section, such as composites thereof with hollow or other polyamide fibers, but a further preferable form is an average degree of irregularity of the multifilament. Is 1.1 to 4, and the cross-sectional shape of at least one filament of the multifilament is a multilobal cross-section including three or more convex portions and three or more concave portions. The irregularity in the present invention is a ratio of a diameter Do of an circumscribed circle to a diameter Di of an inscribed circle of a cross-section of an arbitrary one of the multifilaments, as shown in FIG. . Generally, clothing filaments are multifilaments, and a plurality of filaments are bundled. The irregularity of each cross section is measured, and the average value is defined as the irregularity of the present invention. For example, the cross section of an elliptical shape can have a degree of irregularity of 1.1 or more, but the elliptical shape increases the moisture absorption and desorption rate because the surface area is larger than a perfect circle. It is also effective to apply false twist. Since the cross-sectional shape is broken by the false twisting, the surface area increases. It is not necessary that all the multifilaments have the same cross-sectional shape, and a similar effect can be obtained by using a mixture of a round and an irregular cross-section. Further, the most preferable form is a so-called multi-leaf cross section having a convex portion and a concave portion. In the case of a multi-leaf cross section having three or more convex parts and three or more concave parts, the surface area is further increased, so that the moisture absorption / release rate is improved. When the number of leaves is increased to five or seven, more preferable performance is obtained. The counting of the convex portions and the concave portions is performed as shown in FIG. First, a base line is drawn so that the cross section has a smooth circular or elliptical shape. A base line is drawn so that the cross-sectional area within the base line and the cross-sectional area of the actual cross section are the same. Next, a portion having a continuously large diameter (A portion in FIG. 2) with respect to the base line is defined as a convex portion, and a portion having a continuously small diameter (B portion in FIG. 2) is defined as a concave portion.

  The fineness of the polyamide fiber of the present invention and the number of filaments are not limited. For example, in the case of stocking, a fineness of about 5 dtex to 22 dtex is used, a fineness of 22 dtex to 56 dtex is preferably used for the inner, and a fineness higher than that of the outer is preferably used. It is possible. In addition, any number of filaments can be selected. In order to improve the feel, it is preferable to reduce the single fiber fineness to about 0.3 dtex. In this case, the moisture absorption / release rate can be improved. Since the physical properties typified by the high elongation properties and the dyeing are low in molecular weight, the influence is small, and it can be adjusted within a known range.

  In the method for producing a polyamide fiber according to the present invention, it is necessary to pay attention to the fact that the peak on the low molecular weight side moves, and the control can be performed by the above-mentioned conditions, but other conditions for producing the yarn are affected. Is small. For this reason, it is possible to select any of the conventionally used yarn-making methods, and it is possible to select a one-step method which is advantageous in cost, a two-step method which is a conventional method, POY spinning for performing false twisting, and composite spinning. An example of such a method is as follows. In addition, known methods such as a die to be used, cooling, an applied oil agent, entanglement, and winding can be applied.

  The obtained fiber can be subjected to known yarn processing such as false twist processing, twisting processing, and composite processing represented by Taslan processing, and there is no decrease in the moisture absorption rate due to the processing. Conversely, processing in which the cross-sectional shape becomes irregular is preferable processing. Further, it can be developed for any use of woven or knitted fabric, and is preferably developed for clothing. It is preferably used for innerwear and underwear such as stockings and underwear, mid layers, outerwear, and the like. Particularly, sports innerwear that requires a moisture absorption / release rate is a particularly preferred use.

  Hereinafter, the present invention will be described more specifically with reference to examples. In addition, the measuring method of the characteristic value in an Example is as follows.

(1) Relative viscosity 0.25 g of a sample was dissolved in 100 ml of sulfuric acid having a concentration of 98% by weight so as to be 1 g, and the flow time (T1) at 25 ° C. was measured using an Ostwald viscometer. Subsequently, the falling time (T2) of only 98% by weight sulfuric acid was measured. The ratio of T1 to T2, that is, T1 / T2, was defined as the relative viscosity of sulfuric acid (two significant figures).

(2) Fineness 1. Set the fiber sample in a measuring instrument of 1.125 m / perimeter, rotate it 200 times to make a loop-shaped skein, dry it with a hot air dryer (105 ± 2 ° C. × 60 minutes), and balance it. The weight was measured, and the fineness was calculated from the value obtained by multiplying by the official moisture content. The official moisture regain of the core-sheath composite yarn was 4.5% by weight.

(3) PVP content The fiber was weighed so that the polyamide resin content in the polyamide fiber was 2.5 mg, and dissolved in 4 ml of hexafluoroisopropanol (added with 0.005 N-sodium trifluoroacetate) at a polymer concentration of 6.2 ppm. HPLC measurement was performed using a solution obtained by filtration with a 0.45 μm filter. The pump used was Waters 515 (manufactured by Waters), the detector was Waters 410 (manufactured by Waters), the column was Shodex HFIP-806M (two) + HFIP-LG, and the flow rate was 0.5 ml / min. The injection volume was 0.1 ml and the temperature was measured at 40 ° C. A calibration curve of PVP was prepared in advance, and the content was quantified (rounded to one decimal place).

(4) Measurement of molecular weight distribution The fiber was weighed so that the polyamide resin content in the polyamide fiber was 2.5 mg, and dissolved in 4 ml of hexafluoroisopropanol (added with 0.005 N-sodium trifluoroacetate) at a polymer concentration of 6.2 ppm. GPC measurement was performed using a solution obtained by filtration with a filter having a pore size of 0.45 μm. The pump used was Waters 515 (manufactured by Waters), the detector was Waters 410 (manufactured by Waters), the column was Shodex HFIP-806M (two) + HFIP-LG, and the flow rate was 0.5 ml / min. The injection volume was 0.1 ml and the temperature was measured at 40 ° C. Molecular weight calibration was performed using polymethyl methacrylate. Peak position by the supplied analysis tools, read the peak intensity, low molecular weight side peak molecular weight (three significant figures), the ratio I _L of the peak strength of the low molecular weight side (I _L) and high molecular weight side of the peak intensity (I _H) / I _H (rounded to two decimal places).

(5) Average Degree of Deformity, Number of Concavo-convex Cross Section Photographs (2,000 times) of all multifilaments of polyamide fiber were taken, and the diameters of the circumscribed circle (Do) and the inscribed circle (Di) of each single yarn were measured. The ratio Do / Di was calculated, and the average value of Do / Di of the multifilament was defined as the average irregularity (two significant figures). Regarding the number of cross-sectional irregularities, the multi-filament having the largest number of concavities and convexities was defined as the number of cross-sectional irregularities. For example, in the case of a round cross-section, the number of cross-sectional irregularities is 0, but in the case of a mixed fiber of a round cross-section and a 6-leaf cross-section, the number of cross-sectional irregularities is 6.

(6) ΔMR
A cylinder knitting fabric was produced by adjusting the degree to 50 with a cylinder knitting machine. When the fineness of the fibers is low, the yarns fed to the tubular knitting machine are appropriately plied so that the total fineness of the fibers is 50 to 100 dtex. Was carried out with a single wire, and adjusted so that the degree became 50 as described above. About 1-2 g of this tubular knitted fabric was weighed into a weighing bottle, kept at 110 ° C. for 2 hours, dried, and its weight was measured (W0). Next, the target substance was kept at 20 ° C. and a relative humidity of 65% for 24 hours, and then its weight was measured (W65). Then, after maintaining this at 30 ° C. and a relative humidity of 90% for 24 hours, the weight was measured (W90). And it calculated according to the following formula (two significant figures). ΔMR is good when it is 2.6% or more, and very good when it is 3% or more.
MR1 = [(W65−W0) / W0] × 100% (A)
MR2 = [(W90−W0) / W0] × 100% (B)
ΔMR = MR2-MR1 (C)

(7) Moisture absorption and desorption rate The same tubular knitted fabric as in (6) was allowed to stand at 20 ° C. and a relative humidity of 65% for 24 hours, placed in a closed container, and then transferred to an environment of 30 ° C. and a relative humidity of 90%. . Under the environment, the sample was taken out of the sealed container and the change in weight for 5 minutes was read. The weight change per minute is read from the weight (W1) immediately after being taken out of the closed container and the weight (W2) after 3 minutes, calculated by the following formula, and the moisture absorption / desorption rate (ppm / min, 2 significant figures) ). The moisture absorption / desorption rate is good at 750 ppm / min or more, and very good at 900 ppm / min or more.
Moisture absorption / release rate = [(W2)-(W1)] / 3 x 1,000,000 (D)

(8) Elution rate After the same tubular knitted fabric as in (6) was dried at 110 ° C for 8 hours, the weight was measured (W3). Then, after treating with boiling water for 30 minutes, drying was performed again at 110 ° C. for 8 hours, and then the weight was measured (W4). The weight loss rate before and after the treatment was calculated as an elution rate (%) according to the following formula (two significant figures). The dissolution rate is good at 5% or less, and very good at 4% or less.
Elution rate = [{(W3) − (W4)} / (W3)] × 100

(9) Comprehensive evaluation ΔMR, moisture absorption / release rate, and dissolution were comprehensively evaluated, and classified into three stages of ◎, 、, and ×. ◎ is very good (passed), は is good (passed), and × is not good.

Example 1
A polyamide resin was prepared by kneading 2.0 wt% of nylon 6 having a weight average molecular weight of 1400 and 3.0 wt% of PVP with nylon 6 having a relative viscosity of 2.7. In order to suppress a change in the molecular weight after forming the fiber, the water content of the resin was set to 0.1 wt%, and the time from polymer melting to discharge of the die was set to 13 minutes. According to a standard method of a one-step method, a polyamide fiber having a 33dtex-26 filament and all filaments having a round cross section was produced. The low molecular weight side peak molecular weight of the polyamide fiber was 1430, and the ratio of peak intensity I _L / I _H was 0.04.
The obtained polyamide fiber had a ΔMR of 2.8%, a moisture absorption / release rate of 780 ppm / min, and an elution rate of 1.8%, showing excellent properties.

Examples 2 and 3
A polyamide fiber was produced in the same manner as in Example 1, except that PVP was 3.7 wt% in Example 2 and PVP was 4.1 wt% in Example 3. Low molecular weight side peak molecular weight and the ratio _I L / _{I H} of the peak intensities, respectively in Examples 2 1440,0.04 to give the polyamide fibers are each in Example 3 1430,0.04. By increasing the amount of PVP, the ΔMR was improved to 3.0% and 3.1%, and the moisture absorption / release rate was also improved to 830 ppm / min.

Comparative Example 1
A polyamide fiber was produced in the same manner as in Example 1 except that the amount of PVP was changed to 2.5 wt%. The amount of PVP was small, ΔMR was insufficient at 2.5%, and the moisture absorption / release rate was not satisfactory.

Examples 4 and 5
A polyamide fiber was produced in the same manner as in Example 3, except that the ratio I _L / I _H of the polyamide fiber was adjusted to 0.02 in Example 4 and to 0.07 in Example 5. Although ΔMR, which is a conventional index, does not change significantly, the rate of moisture absorption and desorption is significantly improved by increasing the intensity of the low molecular weight peak, and in Example 5, a favorable result of 960 ppm / min was obtained.

Comparative Examples 2 and 3
A polyamide fiber was produced in the same manner as in Example 3, except that the ratio I _L / I _H of the polyamide fiber was adjusted to 0.01 in Comparative Example 2 and to 0.12 in Comparative Example 3. The ΔMR was as good as 3.1%, but in Comparative Example 2, the rate of moisture absorption and desorption was insufficient, and in Comparative Example 3, the dissolution was insufficient, and all were rejected.

Examples 6 to 11
The amount of PVP to be kneaded was 6.0 wt%, and the molecular weight of low-molecular-weight nylon 6 was further changed. As shown in Table 3, a polyamide fiber having a low-molecular-weight peak having a molecular weight of 1,000 to 2,500 was obtained. The lower the molecular weight, the better the moisture absorption and desorption properties, while the higher the molecular weight, the better the elution properties, all of which were polyamide fibers having excellent properties. The results of Examples 6, 7, 9 to 11 are shown in Table 3, and the results of Example 8 are shown in Table 5.

Comparative Examples 4 and 5
A polyamide fiber having a low molecular weight side peak having a molecular weight of 790 or 2830 was prepared and evaluated. When the molecular weight was low, the dissolution property was insufficient, and when the molecular weight was too high, the rate of moisture absorption and desorption was insufficient, and all were rejected.

Example 12
Except that containing PVP 13.0 wt% will produce a polyamide fiber in the same manner as in Example 8, the molecular weight of the low molecular weight side peak _{1620, I} L / I _H to obtain a polyamide fiber is 0.04. The ΔMR was 6.7%, the moisture absorption / release rate was 1080 ppm / min, and the elution rate was 4.3%, which was good.

Example 13
As another additive, a polyamide fiber was produced in the same manner as in Example 8 except that 2.0 wt% of titanium dioxide was added to obtain a fiber of 11 dtex-10 filament. The effect of adding titanium dioxide was not observed, and the result was good.

Example 14
A polyamide fiber was obtained in the same manner as in Example 8, except that the cross-sectional shape of all the filaments was 25% hollow and the fibers were 25 dtex-26 filaments. Even with hollow fibers, good performance was exhibited.

Examples 15 to 18
A polyamide fiber was produced in the same manner as in Example 8, except that the cross-sectional shape was changed from the round cross-section as shown in Table 5.
Example 15 had an elliptical cross section in which the irregularity of all the filaments was 2.5. As compared with Example 8, the rate of moisture absorption / release was slightly improved, and the effect of deforming was confirmed.
In Example 16, all the filaments had the four-leaf cross section of FIG. In this case, the average degree of irregularity is 1.5, and the number of cross-sectional irregularities is 4. The moisture absorption / desorption rate of this polyamide fiber was increased to 920 ppm / min, and good results were obtained.
In Example 17, all the filaments had the cross-section of the flat eight leaves shown in FIG. In this case, the average degree of irregularity is 3.7, and the number of cross-sectional irregularities is 8. The moisture absorption and desorption rate of this polyamide fiber was 1020 ppm / min, and the effects of the degree of irregularity and the number of cross-sectional irregularities could be confirmed.
In Example 18, 13 filaments were made into a round cross section, the remaining 13 filaments were made into a 6-leaf cross section having a degree of irregularity of 1.4, and a test was carried out by further adding 2 wt% of titanium dioxide. The average degree of irregularity is 1.2, and the number of cross-sectional irregularities is 6. As shown in Table 5, good moisture absorption and desorption rates were exhibited.

Example 19
The same polyamide resin as in Example 8 was used as a partially oriented yarn (POY) of 41 dtex-26 filament, and subjected to false twisting to obtain a polyamide fiber of 33 dtex-26 filament. Since the false twisting was performed, the cross-sectional shape collapsed, and the average irregularity was 1.3. Since it collapsed randomly, the number of cross-sectional irregularities was not determined and was set to zero. The moisture absorption and desorption rate of the obtained fiber was higher than that of Example 8, and the effect was observed even when the fiber was deformed by false twisting.

Comparative Example 6
A polyamide fiber was produced in the same manner as in Example 8, except that the molecular weight of the low molecular weight side peak was 810, the peak intensity ratio I _L / I _H was 0.01, and the cross-sectional shape was flat eight leaves. As is clear from Table 5, although it has a flat 8-leaf cross section, the rate of moisture absorption and desorption was not satisfactory.

  This application is based on Japanese Patent Application No. 2017-059427 filed on March 24, 2017, the contents of which are incorporated herein by reference.

  The polyamide fiber of the present invention can provide a polyamide fiber having a high moisture absorption / release rate, and can provide comfortable clothing.

A: convex portion B: concave portion

Claims (4)

Polyamide and a polyamide fiber containing 3 to 15 wt% of polyvinylpyrrolidone, wherein the polyamide satisfies the following characteristics:
(1) the molecular weight distribution has two peaks, and the molecular weight of the low molecular weight side peak is 1000 to 2500;
(2) In the molecular weight distribution, a ratio I _L / I _H of a peak intensity (I _L ) on a low molecular weight side to a peak intensity (I _H ) on a high molecular weight side is 0.02 to 0.10.   The polyamide fiber according to claim 1, wherein the average degree of irregularity of the filament constituting the polyamide fiber is 1.1 to 4.   The polyamide fiber according to claim 2, wherein the cross-sectional shape of at least one filament constituting the polyamide fiber is a multilobal cross-section having three or more convex portions and three or more concave portions.   A textile product comprising at least a part of the polyamide fiber according to claim 1.

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