TWI901861B - Polyamide crimped yarn, false twist processed yarn and fabrics - Google Patents

Abstract

This invention provides a polyamide latently wound composite fiber that suppresses shrinkage deviation and exhibits good quality with fewer wrinkles/creases caused by uneven dyeing and uneven wounding. The polyamide wound yarn of this invention comprises parallel or eccentric core-sheath type composite polyamide fibers, with a wet-heat shrinkage stress variation rate of less than 150%.

Description

Polyamide crimped yarn, false twist processed yarn and fabrics

The present invention relates to a crimped yarn, false twist processed yarn and fabric containing parallel type or eccentric core-sheath type composite polyamide fiber.

Previously, polyamide fibers were softer and had a better touch than polyester fibers, and were widely used in clothing applications. Single fibers containing one type of polymer, such as nylon 6 or nylon 66, which are representative polyamide fibers for clothing, have basically no stretchability on their own. Therefore, they can be given stretchability by performing false twist processing or the like, and are used in stretchable knitted fabrics. However, it is difficult to obtain a knitted fabric with sufficient stretchability when such a single fiber is subjected to processing such as false twisting.

Therefore, there are methods for obtaining stretchable woven fabrics by using elastic fibers; or by combining two polymers with different properties to create a composite fiber with potential for curling, which is then achieved through heat treatment such as dyeing.

Furthermore, as a polyamide composite fiber with potential for shrinkage, a composite fiber has also been proposed, consisting of two polyamides with different viscosities arranged in a side-by-side or eccentric core-sheath configuration (see Patent 1, Patent 2, and Patent 3).

For example, Patent Document 1 discloses a product containing polym-xylene A false-twisted yarn of a side-by-side type composite yarn in which a resin composition of diamide and polyamide 6 is used as one of the components. In addition, Patent Document 2 discloses a polyamide latent crimp yarn, which contains nylon 6/66 copolymer as a high-viscosity polymer and nylon 6 as a low-viscosity polymer, and is formed by laminating two types of polyamides with different viscosities in a side-by-side manner. Furthermore, Patent Document 3 discloses a parallel type or eccentric core-sheath type composite polyamide fiber for false twisting, which contains nylon 610 or nylon 612 as a single component of low water-absorbent polyamide.

[Existing technical literature]

[Patent Documents]

[Patent Document 1] Japanese Patent Application Publication No. 2014-80717

[Patent Document 2] Japanese Patent Application Publication No. 2009-57679

[Patent Document 3] Japanese Patent Application Publication No. 2018-3190

However, in the composite fibers described in Patent Document 1 and Patent Document 2, two polymers having different characteristics are bonded together, and there is a problem that the stress applied to each polymer in the spinning and drawing step changes due to a slight viscosity change of each polymer, thereby causing a deviation in the fiber orientation/crystallinity in the length direction. The shrinkage of the crimped yarn or false twisted yarn obtained from the composite fiber has a large variation, resulting in uneven dyeing, uneven crimp, and the like. Furthermore, even those yarns with excellent curl in their raw or processed state are prone to developing wrinkles characteristic of polyamide fibers during the humid heat treatment of the fabric during refining or dyeing. These wrinkles are difficult to eliminate, therefore, tension must be applied to the fabric during the humid heat treatment. As mentioned above, the polyamide composite fibers described in Patents 1 and 2 have the following problem: because tension is applied to the fabric during the humid heat treatment, the curl inherent in the raw or processed yarn cannot be fully realized, resulting in a fabric lacking stretch.

In order to address the problem of wrinkles in polyamide composite fibers, Patent Document 3 describes that by producing side-by-side or eccentric core-sheath type polyamide composite fibers containing nylon 610 or nylon 612 as a single component of low water-absorbent polyamide, wrinkles are less likely to occur during moist heat steps such as dyeing when producing knitted fabrics, and sufficient stretchability can be imparted. However, similar to Patent Document 1 and Patent Document 2, there are problems such as variations in fiber orientation/crystallinity due to slight viscosity fluctuations, variations in shrinkage, uneven dyeing, and uneven crimping in crimped yarns or falsely twisted yarns.

Therefore, the purpose of this invention is to solve the aforementioned problems and to provide a polyamide wound yarn that suppresses shrinkage deviation and has good quality with fewer wrinkles/creases caused by uneven dyeing and uneven wounding.

In order to achieve the above object, the polyamide crimped yarn and false-twisted yarn of the present invention include the following structures.

(1) A polyamide wound yarn comprising parallel or eccentric core-sheath composite polyamide fibers, having a wet-heat shrinkage stress variation rate of less than 150%.

(2) The polyamide shrink yarn described in (1) is formed by bonding two polyamides with different shrinkage properties in a side-by-side or eccentric core-sheath configuration.

(3) The polyamide wound yarn as described in (1) or (2), wherein the wet heat shrinkage stress is 0.001 cN/dtex to 0.50 cN/dtex.

(4) The polyamide wound yarn as described in any one of (1) to (3), wherein the elongation at break is 15% to 100%.

(5) A false-twisted yarn including the polyamide crimped yarn according to any one of (1) to (4).

(6) The false-twisted yarn according to the above (5), wherein the wet-heat shrinkage stress variation rate is 150% or less.

(7) The false-twisted yarn according to (5) above, which has a stretch elongation of 70% to 300%.

(8) A fabric containing the false-twisted yarn according to (7).

According to the present invention, it is possible to provide a stretchable polyamide knitted fabric that suppresses variation in shrinkage that is a problem in polyamide crimped yarns and false-twisted yarns, has few wrinkles/wrinkles caused by uneven dyeing and uneven crimping, and has good quality.

A: Crystalline polyamide (A)

B: Crystalline polyamide (B)

Y: Yarn stripes

L: Distance

M: Length

1: Spun yarn pieces

2: Spinning die opening

3: Cooling device

4-1: Oil supply device (first stage)

4-2: Oil supply device (second stage)

5: Interwoven nozzle device

6: Pulling the chariot

7: Extension Roller

8: Roll-up device

10a~10c: Side-by-side composite polyamide fibers

10d: Eccentric core-sheath type composite polyamide fiber

11: The center of an eccentric core-sheath type composite polyamide fiber

12: The center of the core (serving as the center of the crystalline polyamide (A) in the core)

Figure 1 is a diagram illustrating the morphology of the composite fiber. Figure 1(a) is a cross-sectional view showing the parallel and eccentric core-sheath types, and Figure 1(b) is a diagram illustrating the eccentric arrangement in the eccentric core-sheath type composite fiber.

Figure 2 is a schematic step diagram illustrating an embodiment of a manufacturing apparatus preferably used in the manufacturing method of the polyamide wound yarn of the present invention.

The invention will now be described in more detail.

In this instruction manual, "mass" and "weight" have the same meaning.

The polyamide wound yarn of this invention comprises parallel or eccentric core-sheath composite polyamide fibers, with a wet-heat shrinkage stress variation of less than 150%.

<Two types of polyamide (PA) with different shrinkage properties>

The parallel or eccentric core-sheath structure of the composite polyamide fiber forming the polyamide wound yarn of the present invention is preferably formed by two polyamides with different shrinkage properties. That is, the composite polyamide fiber is composed of crystalline polyamide (A) and crystalline polyamide (B) as the two components with different shrinkage properties. Because both components contain polyamide, the composite interface has high affinity, preventing interface peeling, reducing cross-sectional deviation or poor cross-sectional shape, and allowing for uniform oiling and interweaving. Therefore, polyamide wound yarns with low oil content deviation or interweaving deviation can be obtained.

Examples of polyamides include: nylon 6, nylon 66, nylon 4, nylon 11, nylon 12, nylon 410, nylon 510, nylon 610, nylon 612, and copolymers with these as main components.

Regarding the shrinkage characteristics of crystalline polyamide (A) and crystalline polyamide (B), there are no particular limitations as long as the effectiveness of the invention is not impaired. The preferred difference in boiling water shrinkage rate when each polymer is used as a monofilament yarn is 5.0% or higher. The practical upper limit for the boiling water shrinkage rate difference is 40%.

Furthermore, the boiling water shrinkage rate is calculated by sampling a 33 dtex 12-filament monofilament of the polymer, applying a load of 90 mg/dtex for 30 seconds, determining the length B, then immersing it in boiling water at 100°C for 20 minutes, air-drying it, applying a load of 90 mg/dtex for 30 seconds, determining the length A, and then calculating it according to the following formula.

Boiling water shrinkage rate (%) = [(B-A)/B] × 100

<Crystall Polyamide (A)>

Crystalline polyamide (A) is defined as a type of polyamide different from crystalline polyamide (B) among the illustrated polyamides. Preferably, crystalline polyamide (A) is nylon 6, nylon 66, nylon 4, nylon 610, nylon 11, nylon 12, or copolymers thereof as main components.

As long as it does not impair the effects of the invention, the crystalline polyamide (A) may contain components other than lactamine, aminocarboxylic acid, diamine, and dicarboxylic acid in its repeating structure.

Furthermore, from the viewpoints of yarn-making properties, strength, and peel resistance, the crystalline polyamide (A) is preferably a polymer in which at least 90 moles of the repeating structure are composed of a single lactamine, aminocarboxylic acid, or a combination of diamines and dicarboxylic acids; more preferably, it is a polymer in which at least 95 moles of the repeating structure are composed of a single lactamine, aminocarboxylic acid, or a combination of diamines and dicarboxylic acids.

<Crystall Polyamide (B)>

Crystalline polyamide (B) can be any polymer as long as its shrinkage characteristics differ from those of crystalline polyamide (A). Examples of crystalline polyamides (B) described above are possible. Preferably, crystalline polyamide (B) is nylon 6, nylon 66, nylon 4, nylon 610, nylon 11, nylon 12, etc., and copolymers thereof as main components. Among these, polymers in which at least 90 mol% of the repeating structure is a single lactone, aminocarboxylic acid, or a combination of diamines and dicarboxylic acids are preferred; more preferably, polymers in which at least 95 mol% of the repeating structure is a single lactone, aminocarboxylic acid, or a combination of diamines and dicarboxylic acids are preferred.

<Polyamide Combinations>

The combination of crystalline polyamide (A) and crystalline polyamide (B) in the composite polyamide fiber is preferably a combination of nylon 610 or nylon 612 and nylon 6. By employing this structure, fabrics exhibiting excellent curling properties and possessing superior hand feel, durability, and soft stretch can be formed.

<Additives>

Additionally, depending on the requirements, pigments, heat stabilizers, antioxidants, weathering agents, flame retardants, plasticizers, mold release agents, lubricants, foaming agents, antistatic agents, formability modifiers, and reinforcing agents can be added to crystalline polyamide (A) and crystalline polyamide (B).

<Combined type>

The composite polyamide fiber forming the polyamide wound yarn of the present invention has a composite profile formed by bonding two crystalline polyamides with different shrinkage properties. Preferably, the two crystalline polyamides are substantially inseparable and exist in a bonded state. Examples of composite profile morphologies include, for example, the side-by-side type (symbols 10a-10c) or the eccentric core-sheath type (symbol 10d) shown in Figure 1(a). In the eccentric core-sheath type composite polyamide fiber 10d, the crystalline polyamide (A) (symbol A) as the core component is covered by the crystalline polyamide (B) (symbol B) as the sheath component. Figure 1(a) shows an eccentric core-sheath type composite polyamide fiber 10d, illustrating a structure where crystalline polyamide (A) forms the core. Since only two components with different shrinkage properties are required, crystalline polyamide (B) can also be the core. Specifically, the polyamide on the low-shrinkage side can be located in the core, while the high-shrinkage polyamide, having a higher shrinkage property than the low-shrinkage polyamide, forms the sheath; alternatively, the structures can be reversed.

The interface between crystalline polyamide (A) and crystalline polyamide (B) in the cross-section of the composite polyamide fiber can be flat or smooth. Furthermore, the bonded interface can be straight or curved. By setting the composite morphology of the composite polyamide fiber to a side-by-side or eccentric core-sheath type, curling occurs based on the difference in shrinkage between the two components.

Furthermore, regarding the composite ratio of crystalline polyamide (A) to crystalline polyamide (B), the preferred area ratio in the fiber cross-section perpendicular to the long axis of the fiber is crystalline polyamide (A):crystalline polyamide (B) = 2:1 to 1:2.

In eccentric core-sheath type composite polyamide fibers, as shown in Figure 1(b), the ratio L/M of the distance L between the center 11 of the eccentric core-sheath type composite polyamide fiber 10d and the center 12 of the crystalline polyamide (A) serving as the core, and the length M of the intersection point of the line extending this distance L and the outer perimeter of the yarn, is preferably 1/8 to 1/2. Furthermore, the center of the core refers to the position of the centroid of the core in the cross-section of the fiber.

<Wet heat shrinkage stress change rate/crimp yarn/false twisted yarn>

The polyamide shrinkage yarn of this invention exhibits a wet-heat shrinkage stress variation rate of less than 150%.

By achieving a wet-heat shrinkage stress variation rate of less than 150%, deviations in yarn shrinkage under wet-heat conditions, such as during refining or dyeing processes, can be suppressed, thus reducing uneven dyeing and shrinkage during these steps. The result is a woven fabric with excellent quality and superior tensile strength.

Conversely, if the rate of change in wet-heat shrinkage stress exceeds 150%, uneven dyeing and shrinkage are likely to occur during the refining or dyeing processes, resulting in poor quality and reduced fabric tensile strength.

The optimal rate of change of shrinkage stress under humid conditions is below 120%. Furthermore, the practical lower limit for the rate of change of shrinkage stress under humid conditions is 50%.

In addition, the wet-heat shrinkage stress variation rate of the false-twisted yarn containing the polyamide crimped yarn of the present invention is preferably 150% or less. The wet-heat shrinkage stress change rate of the false-twisted yarn is preferably 120% or less, and the practical lower limit of the wet-heat shrinkage stress change rate is 0.5%. If the wet-heat shrinkage stress variation rate of the false-twisted yarn is within the above range, variation in the shrinkage rate of the false-twisted yarn under wet-heat conditions can be suppressed, thereby reducing uneven dyeing and uneven crimping during the processing step.

The wet-heat shrinkage stress variation rate mentioned here refers to the deviation (coefficient of variation (CV)%) of the shrinkage stress generated during heat treatment under wet-heat conditions, continuously measured axially along the fiber using the Toray Engineering FTA-500 continuous heat shrinkage measuring instrument. In the FTA-500, the yarn travels between the feed roller and the draw roller, and wet-heat treatment is performed using a heated water bath located between the rollers. The shrinkage stress is continuously measured using a tension measuring instrument located behind the bath.

The wet and hot shrinkage stress variation rate is calculated by setting the measurement frequency of the shrinkage stress of each yarn to 6 times per 1cm, taking the average value of 6 measurements as 1 data point, and collecting more than 1000 data points. Based on the 1000 data points obtained, the average value f_{_ave} and standard deviation σ_f are calculated, and then calculated according to the following formula.

Humidity and heat shrinkage stress variation rate (%) = (standard deviation σf) / (mean value f_{_ave} ) × 100

The testing conditions are as follows: the yarn to be tested is set to 25m, the speed ratio of the feed roller to the traction roller is set to 99/100, the heating water tank temperature is set to 100℃, and the yarn speed is set to 5m/min.

<Humid and Thermal Contraction Stress>

In addition, the wet heat shrinkage stress is defined as the value obtained by dividing the average shrinkage stress f _{_ave} obtained by measurement using the continuous heat shrinkage tester "FTA-500" by the total fiber length measured according to Japanese Industrial Standards (JIS) L1013 (2010).

The wet heat shrinkage stress of the polyamide wound yarn of this invention is preferably 0.001 cN/dtex to 0.50 cN/dtex. By setting it within this range, sufficient loop shrinkage can be observed even in fabrics bound with the yarn, thus obtaining fabrics with excellent tensile strength.

The optimal wet-heat shrinkage stress is 0.002 cN/dtex to 0.40 cN/dtex.

<Total fiber density, Single yarn fiber density>

When considering applications in clothing, the total fiber density of the polyamide wound yarn is preferably 20 dtex to 200 dtex. Furthermore, regarding the single yarn fiber density, there are no limitations as long as it does not impair the performance of the invention; however, for applications in sportswear, down jackets, outerwear, and innerwear, a density of 1.0 dtex to 6.0 dtex is preferred.

<Stretch>

The preferred elongation of polyamide crimped yarn is 50% to 80%. By setting it within the above range, the actual number of twists added in the false twisting process becomes appropriate, and uniform crimp is imparted to the obtained processed yarn, thereby obtaining a processed yarn with a reduced change in crimp over time or a reduced reduction in crimp during repeated drawing.

<Elongation at break>

The polyamide wound yarn of this invention preferably has an elongation at break of 15% or more. By setting it within this range, sufficient coil winding is achieved, thereby obtaining a fabric with good softness and stretchability.

The practical upper limit for elongation at break is 100%. For polyamide shrink yarns, the elongation at break is preferably 16% or higher, and more preferably 17% or higher.

In addition, the stretch elongation of the false-twisted yarn of the present invention is preferably 70% or more. By setting it within the above range, sufficient coil crimp is developed, and a fabric with good soft stretchability can be obtained.

The practical upper limit of stretch elongation is 300%. The stretch elongation of the false-twisted yarn is more preferably 75% or more, and more preferably 80% or more.

The elongation at break is determined by: making a 1m circumference loop from scratch, immersing it in boiling water at 90°C for 20 minutes, air-drying it, applying a load of 1.8 mg/dtex for 30 seconds, calculating length A; then applying a load of 90 mg/dtex for 30 seconds, calculating length B; and finally calculating the elongation at break using the following formula.

Elongation at break (%) = [(B-A)/B] × 100

<Manufacturing Method>

The manufacturing method of the polyamide wound yarn of this invention will be described.

In the manufacturing method of the polyamide wound yarn of this invention, the polyamide on the low-shrinkage side preferably suppresses the viscosity increase during melt retention. It is known that polyamides undergo polymerization reactions due to retention during melt spinning, resulting in an increase in viscosity. Therefore, by adjusting the chip moisture content of the polyamide on the low-shrinkage side and controlling the polymerization equilibrium reaction, the viscosity increase caused by retention during melt spinning can be suppressed.

Regarding the polyamide on the low-shrinkage side, when the melt viscosity immediately after melting in the molten yarn is set as η0, and the melt viscosity just before exiting the spinning die is set as ηs, it is preferable that ηs - η0 ≤ 50 poise. By keeping ηs - η0 below 50 poise, the viscosity increase of the low-shrinkage polyamide can be suppressed, and the stress during yarn stretching is appropriately applied to the high-shrinkage side polyamide, resulting in poor alignment and thus better potential curl. ηs - η0 is further preferably -150 poise ≤ ηs - η0 ≤ 50 poise. By setting etas-eta0 to -150 poise or more, it is possible to suppress variations in the melt viscosity of the polymer in the spinning pipe, stabilize the fiber structure of the composite fiber, suppress variations in the shrinkage of crimped yarns or falsely twisted yarns under moist and hot conditions such as refining steps or dyeing processing steps, and reduce uneven dyeing and uneven crimping during these steps.

When using nylon 610 (with a relative viscosity of 2.7 for sulfuric acid) as a low-shrinkage polyamide, the optimal fragment moisture content is 600 ppm to 1800 ppm. By maintaining a polyamide moisture content below 1800 ppm, hydrolysis of the polyamide is suppressed during retention in the melt, piping, and spinning die, preventing extreme viscosity reduction and thus stabilizing melt viscosity variations. Furthermore, yarn warping during die ejection is suppressed, enabling stable operation.

Furthermore, the relative viscosity of sulfuric acid is determined by dissolving 0.25g of polyamide in 25ml of 98% by mass sulfuric acid at a concentration of 1g/100ml, measuring the flow time (T1) at 25°C using an Ostwald viscometer, and then calculating it as T1/T2, relative to the flow time (T2) of 98% by mass sulfuric acid only.

Regarding the difference in relative viscosity of sulfuric acid between crystalline polyamide (A) and crystalline polyamide (B), there is no limitation as long as it does not impair the effects of the present invention; a range of 0.5 to 1.0 is preferred. By setting the relative viscosity difference of sulfuric acid to 0.5 or higher, it is easier to generate a difference in stress applied to each polyamide during yarn making, which can produce a difference in alignment, thereby obtaining high potential winding performance. Conversely, by setting it to 1.0 or lower, yarn bending caused by the viscosity difference can be suppressed during yarn making, thereby enabling stable yarn making.

The melt viscosity difference between crystalline polyamide (A) and crystalline polyamide (B) is preferably below 1000 poise. A melt viscosity difference below 1000 poise can suppress yarn warping during die ejection, enabling stable yarn production, which is therefore preferable. A melt viscosity difference of 600 to 1000 poise is even more desirable. A melt viscosity difference above 600 poise easily generates stress differences on each polyamide during spinning, leading to poor alignment and thus easily obtaining composite polyamide fibers with excellent potential shrinkage properties.

Furthermore, the composite polyamide fiber forming the polyamide wound yarn of this invention has a composite profile formed by bonding two crystalline polyamides. In the parallel type, when the difference in melt viscosity between the two polyamides is large, the polymer flow resistance during die ejection is different, and the difference in flow velocity tends to cause yarn bending and deteriorate yarn stability. Therefore, in the manufacture of composite polyamide fibers using crystalline polyamide (A) and crystalline polyamide (B) with different melt viscosities, from the viewpoint of yarn stability, an eccentric core-sheath type is preferred.

Secondly, the manufacturing method based on high-speed direct spinning will be explained.

Crystalline polyamide (A) and crystalline polyamide (B) are melted separately, metered and transported using a gear pump, and a composite flow is formed directly using conventional methods to achieve a parallel or eccentric core-sheath type. The composite fiber is ejected from the spinning die (spinning die 2 of spinning block 1 in Figure 2) in the manner illustrated in Figure 1(a) with a cross-section. The ejected composite polyamide fiber yarn Y is cooled to 30°C by blowing cooling air through a yarn cooling device 3 such as a chimney. Next, the cooled yarn is oiled and bundled using oil supply devices (first stage) 4-1 and (second stage) 4-2. After being interlaced by the interlacing device (interlacing nozzle device 5), it is drawn by the traction roller 6 at a speed of 2000 m/min to 4500 m/min (spinning speed), passing between the traction roller and the extension roller 7. During this process, the yarn is extended at a ratio of 1.0 to 1.5 times, depending on the ratio of the circumferential speed of the traction roller to the extension roller. Then, the yarn is wound into a package (winding device 8) at a speed of 3000 m/min or higher.

The optimal spinning speed is 2000 m/min to 3500 m/min. Setting the speed above 2000 m/min results in a large yarn draft up to the traction roller, which easily creates stress differences on the various polyamide fibers, leading to poor alignment and thus obtaining composite polyamide fibers (polyamide wound yarn) with excellent potential shrinkage properties. Setting the speed below 3500 m/min suppresses yarn warping at the die exit, resulting in stable yarn production.

The false-twisted yarn of the present invention can be obtained by a previously known false-twisting method. It is preferable to use an extension friction false twist processing device to perform false twist processing. Examples are as follows. For example, the polyamide crimped yarn of the present invention supplied to the stretching friction false twist processing device is sent to the supply roller via a desired yarn path guide or fluid treatment device. Thereafter, the yarn is guided to a drawing roller through a heated false twist heater, a cooling plate, and a twisting body that performs draw friction and false twisting, and is wound up as a false twisted processed yarn. As the drawing friction false twisting, the friction false twisting process can be performed before the supply roller of the drawing friction false twisting processing device and after stretching using a hot pin or a hot plate, or the friction false twisting process can be performed while extending between the supply roller and the stretching roller.

The twisting method is not limited to the spindle method, the 3-axis twisting machine method, the belt clamping method, and the like. When you want to strengthen the crimping, it is better to use the spindle method. When you want to increase the processing speed and reduce the production cost, it is better to use a 3-axis twisting machine and belt clamping that are friction false twisting methods.

The polyamide crimped yarn and false-twisted yarn of the present invention can be woven and knitted according to known methods. The obtained fabric and knitted fabric have excellent stretchability.

In the case of fabrics, the weave can be plain weave, twill weave, satin weave, or any variation or blend thereof, depending on its intended use.

In the case of knitted fabrics, the weave structure, depending on its intended use, can be any of the following: plain knit for circular knitting, double rib knit, semi-knit for warp knitting, satin knit, jacquard knit, or variations and blends of these.

In addition, the use of the knitted fabric containing the polyamide crimped yarn and false-twisted yarn of the present invention is not limited, but is preferably used for clothing, and more preferably for down jackets, windbreakers, etc. Golf clothes, raincoats, etc. are representative sports, casual wear or clothing materials for women and gentlemen. It is particularly suitable for use in sportswear and down jackets.

[Implementation Example]

Secondly, the composite polyamide fiber of this invention will be specifically illustrated through embodiments.

A. Melting point:

Thermal analysis was performed on polyamide fragment samples using a Q1000 instrument manufactured by TA Instruments, and data processing was performed using Universal Analysis 2000. The thermal analysis was conducted under nitrogen gas (50 mL/min), at a temperature range of -50°C to 300°C, a heating rate of 10°C/min, and with a fragment sample mass of approximately 5 g (calorific data were standardized after measurement). The melting point was determined based on the melting peak.

B. Relative viscosity:

A 0.25 g sample of polyamide fragments was dissolved in 25 ml of 98% (w/w) sulfuric acid at a concentration of 1 g/100 ml. The flow time (T1) at 25°C was measured using an Oswald viscometer. Then, the flow time (T2) was measured only for 98% (w/w) sulfuric acid. The ratio of T1 to T2, T1/T2, is defined as the relative viscosity of the sulfuric acid.

C. Melt viscosity (capillary plotter):

For polyamide fragment samples, the moisture content was adjusted to the specified value as described in Tables 1-3. A capillary plotter 1B manufactured by Toyo Seiki Co., Ltd. was used to measure the strain rate in stages and the melt viscosity. The measurement temperature was set to the same as the spinning temperature, and measurements were taken at three points: 5 minutes, 10 minutes, and 20 minutes after the sample was added to the heating furnace until the start of the measurement (holding time). Furthermore, in the embodiments or comparative examples, the melt viscosity at 1216 ^s⁻¹ when the holding time was set to 5 minutes was recorded. The value obtained by subtracting the minimum value from the maximum value of the melt viscosity at 1216 ^s⁻¹ at each holding time (maximum value - minimum value) was set as the melt viscosity variation range.

D. Fragment moisture content:

For polyamide fragment samples, a CA-200 micro-moisture analyzer (manufactured by Mitsubishi Chemical Co., Ltd.) was used. The Karl Fischer electrostatic titration method was employed. An electrolyte primarily composed of iodide ions, sulfur dioxide, and alcohol was added to the titration cell. Iodine required for titration was generated internally through electrolysis. The amount of electricity required for electrolytic oxidation was accumulated, and the moisture content was calculated.

E. Boiling water shrinkage rate of monofilament yarn:

Using the polymers described in the embodiments as raw materials, melt-blown extrusion was performed at a temperature of 280°C using a spinning die with 12 extrusion orifices. The resulting yarn was cooled, oiled, and interwoven, then drawn using a traction roller at 2570 m/min, and subsequently stretched to 1.7 times its original length. It was then heat-fixed at 155°C, and a 33 dtex 12-filament polyamide monofilament was obtained at a winding speed of 4000 m/min. The obtained fiber sample was spun and sampled, and a load of 90 mg/dtex was applied for 30 seconds to determine the length B. Next, after immersion in boiling water at 100°C for 20 minutes, the sample was air-dried and then subjected to a load of 90 mg/dtex for 30 seconds. The length A was then calculated. The shrinkage rate of the boiling water was calculated using the following formula.

Boiling water shrinkage rate (%) = [(B-A)/B] × 100

F. Total Fiber:

According to JIS L1013 (2010), for fiber samples, 200 spun yarns were produced using a measuring machine with a frame circumference of 1.125 m and a tension of 1/30 (g). The yarn was dried at 105°C for 60 minutes and then transferred to a desiccator for cooling at 20°C and 55% RH for 30 minutes. The mass of the spun yarn was measured, and the mass per 10,000 m was calculated based on the obtained values. The total fiber density was calculated by setting the standard moisture content to 4.5%. Five measurements were performed, and the average value was taken as the total fiber density.

G. Humid-heat shrinkage stress, rate of change of humid-heat shrinkage stress:

Using a heat shrinkage stress tester (manufactured by Toray Engineering, model "FTA-500"), the fiber yarn to be tested was set to 25m, the speed ratio of the feed roller to the traction roller was set to 99/100, and a tension of 1/50g of the yarn's decitex was applied. The test was conducted under humid conditions with a set temperature of 100°C in a heated water bath, a yarn speed of 5m/min, and the obtained shrinkage stress was used to calculate the humid heat shrinkage stress and the humid heat shrinkage rate according to the following formulas.

Humidity and heat shrinkage stress (cN/dtex) = (average value f _{_ave} ) / (total fiber density)

Humidity and heat shrinkage stress variation rate (%) = (standard deviation σf) / (mean value f_{_ave} ) × 100

H. Elongation at break:

Prepare a 1m circumference yarn from the self-fiber sample. Immerse it in boiling water at 90°C for 20 minutes, then air dry. Apply a load of 1.8 mg/dtex for 30 seconds and calculate length A. Then apply a load of 90 mg/dtex for 30 seconds and calculate length B. Calculate the elongation at break using the following formula.

Elongation at break (%) = [(B-A)/B] × 100

I. Strength and Elongation:

Fiber samples were tested using the "TENSILON" (registered trademark) UCT-100 standard manufactured by Orientec under constant elongation conditions as described in JIS L1013 (Test Methods for Chemical Fiber Filaments, 2010). Elongation was determined from the elongation at the point representing maximum strength in the tensile strength-elongation curve. Strength was calculated by dividing the maximum strength by the fiber length. Ten measurements were performed, and the average value was used as both strength and elongation.

J. Fabric Evaluation:

(a) Manufacturing of weft yarn

Using N6 (relative viscosity 2.70, melting point 222℃), melt-blown yarn was produced at 275℃ using a spinning die with 12 nozzles. After melt-blowing, the resulting yarn was cooled, oiled, and interwoven. It was then drawn using traction rollers at 2570 m/min, stretched to 1.7 times its original length, and heat-fixed at 155℃. A 70 dtex 12-filament nylon 6 yarn was obtained at a winding speed of 4000 m/min.

(b) Fabrication

The side-by-side or eccentric core-sheath type polyamide composite false-twisted processed yarns obtained in Examples 1 to 10 and Comparative Examples 1 to 4 were used as warp yarns (warp density 90 yarns/2.54cm), use the nylon 6 yarn strips obtained in (a) as weft yarn (weft yarn density 90 yarns/2.54cm) to weave plain fabric (warp yarn/processed yarn).

The obtained fabric was spun at 80°C for 20 minutes, then adjusted to pH 4 using Kayanol Yellow N5G 1% owf and acetic acid, and dyed at 100°C for 30 minutes. Following this, a fixation treatment was performed at 80°C for 20 minutes. Finally, to improve the hand feel, a heat treatment was performed at 170°C for 30 seconds.

(c) Elongation (stretchability) of the fabric in the warp direction

The elongation of the fabric in the warp direction was measured according to the JIS L1096 method for fabrics under constant load (Method B, 2010). Tensile properties were evaluated in three stages. Furthermore, an evaluation of "A" indicates sufficient tensile strength.

A: More than 15%

B: 5% or more, but less than 15%

C: Less than 5%

(d) Fabric quality

The quality of the fabric's radial stripes is confirmed through visual inspection by experienced inspectors, and is evaluated in four stages. Furthermore, evaluations of "A" and "B" represent the practical standard.

A: Good

B: Slightly good (not a flaw, but stripes are visible)

C: Slightly defective (Although there are defects such as uneven dyeing or streaks, it can be used by cutting around the defective areas, or by using the specified color in the finished product)

D: Defective (Issues such as uneven dyeing or streaks prevent it from being used as a finished product)

[Implementation Example 1]

Nylon 6 (N6) with a relative viscosity of 2.6, melting point of 222°C, boiling water shrinkage of 13.0% for monofilament yarn, and moisture content of 50 ppm was used as crystalline polyamide (A). Nylon 610 (N610) with a relative viscosity of 2.7, melting point of 225°C, boiling water shrinkage of 7.0% for monofilament yarn, and moisture content of 1400 ppm was used as crystalline polyamide (B). Crystalline polyamide (A) and crystalline polyamide (B) were melted separately and melt-blown using a parallel composite fiber spinning die (12 holes, round holes) at a composite ratio (mass ratio) of 5:5 for crystalline polyamide (A): crystalline polyamide (B) (spinning temperature 270°C). Regarding the yarn ejected from the die nozzle, a yarn cooling device is used to cool and solidify the yarn. As shown in Table 1, a water-containing oil agent containing wax is supplied via a two-stage oil supply device. After interlacing via a fluid interlacing nozzle, the yarn is tractioned at 3700 m/min using traction rollers (room temperature 25°C), and then extended at 1.15 times the length between extension rollers (room temperature 25°C). Finally, the yarn is wound at a take-up speed of 4000 m/min.

A polyamide potential crimped composite yarn with 63 dtex 12 filament, elongation at break of 17.4%, and wet heat shrinkage stress variation of 100% was obtained.

Using the obtained polyamide latent crimp composite fiber yarn, pin false twisting was carried out under the conditions of twist number (D/Y) 1.95 while applying a stretch magnification of 1.25 at a heater temperature of 190°C to obtain a false twisted processed yarn with a stretch elongation rate of 140%. The obtained false-twisted yarn is used as warp yarn to weave plain fabric. The fabric obtained has excellent stretchability and fabric quality. The results are shown in Table 1.

[Implementation Example 2]

The moisture content of crystalline polyamide (B) was set to 1100 ppm, and melt-blown using a parallel-type composite fiber spinning die (12-hole, round hole), it was stretched to 1.10 times between stretching rollers (room temperature 25°C). Otherwise, using the same method as in Example 1, a 63 dtex 12 filament polyamide potential wound composite fiber yarn with an elongation at break of 18.1% and a wet-heat shrinkage stress change rate of 110% was obtained.

The obtained polyamide latent crimp composite fiber yarn was pinned and false-twisted using the same method as in Example 1 to obtain a false-twisted yarn with a stretch elongation of 145%. The obtained false-twisted yarn is used as warp yarn to weave plain fabric. The fabric obtained has excellent stretchability and fabric quality. The results are shown in Table 1.

[Implementation Examples 3 and 4]

Except for changing the moisture content of the crystalline polyamide (B) as shown in Table 1, the polyamide potential wound composite yarn was obtained using the same method as in Example 1.

The obtained polyamide latent crimp composite fiber yarn strips were pinned and false-twisted using the same method as in Example 1, and the obtained false-twisted processed yarns were used as warp yarns to weave plain fabrics. The obtained fabric has excellent stretchability. Regarding fabric quality, Example 3 was good and Example 4 was slightly good. The results are shown in Table 1.

[Implementation Example 5]

As shown in Table 2, an eccentric core-sheath type composite fiber spinning die (12 holes, round holes) is used to perform melt ejection at a spinning temperature of 290°C. In a two-stage oil supply, a water-containing oil for false twisting is used as the second stage oil. The oil is drawn by a traction roller (room temperature 25°C) at 3000m/min, stretched between the stretching rollers (room temperature 25°C) at 1.20 times, and then the package is rolled up at a winding speed of 3582m/min, except for Except for this, use the same method as in Example 1 to obtain 66dtex Polyamide latent crimped composite yarn with 12 filaments, 19.5% elongation at break, and 100% wet-heat shrinkage stress variation.

The obtained polyamide latent crimp composite fiber yarn was rubbed and false-twisted to obtain a false-twisted yarn with a stretch elongation of 165%. The obtained false-twisted yarn is used as warp yarn to weave plain fabric. The fabric obtained has excellent stretchability and fabric quality. The results are shown in Table 2.

[Implementation Examples 6-8]

Except for changing the moisture content of the crystalline polyamide (B) as shown in Table 2, the polyamide potential wound composite yarn was obtained using the same method as in Example 5.

The obtained polyamide latent crimp composite fiber yarn strips were frictionally false-twisted using the same method as in Example 5, and the obtained false-twisted yarns were used as warp yarns to weave plain fabrics. The obtained fabric has excellent stretchability. Regarding fabric quality, Examples 6 and 7 were found to be good, and Example 8 was slightly good. The results are shown in Table 2.

[Implementation Example 9]

The traction roller speed was set to 2218 m/min, the stretch ratio between the traction roller and the extension roller was set to 1.45, and the package was wound at a take-up speed of 3200 m/min. Otherwise, the polyamide potential wound composite yarn was obtained using the same method as in Example 5.

The obtained polyamide latent crimp composite fiber yarn was frictionally false-twisted using the same method as in Example 5, and the obtained false-twisted yarn was used as a warp. Yarn to weave plain fabrics. The fabric obtained has excellent stretchability and fabric quality. The results are shown in Table 2.

[Implementation Example 10]

Except for replacing the polymers of crystalline polyamide (A) and crystalline polyamide (B), the polyamide potential wound composite yarn is obtained using the same method as in Example 5.

The obtained polyamide latent crimp composite fiber yarn strips were frictionally false-twisted using the same method as in Example 5, and the obtained false-twisted yarns were used as warp yarns to weave plain fabrics. The fabric obtained has excellent stretchability and fabric quality. The results are shown in Table 2.

[Table 1]

[Table 2]

[Comparative example 1]

Except for using nylon 610 (N610) with a relative viscosity of 2.7, a melting point of 225°C, and a moisture content of 200 ppm as the crystalline polyamide (B), a polyamide potential wound composite yarn with a 63 dtex 12 filament, an elongation at break of 15.3%, and a wet heat shrinkage stress variation of 210% was obtained using the same method as in Example 1.

The obtained polyamide latent crimp composite fiber yarn was pinned and false-twisted using the same method as in Example 1 to obtain a false-twisted yarn with a stretch elongation of 130%. The obtained false-twisted yarn is used as warp yarn to weave plain fabric. The obtained fabric had excellent stretchability, but the fabric quality was poor. The results are shown in Table 3.

[Comparative example 2]

Except for setting the moisture content of the crystalline polyamide (B) to 2000 ppm, a polyamide potential wound composite yarn with a 63 dtex 12 filament, an elongation at break of 17.1%, and a wet-heat shrinkage stress variation of 180% was obtained using the same method as in Example 1.

The obtained polyamide latent crimp composite fiber yarn was pinned and false-twisted using the same method as in Example 1 to obtain a false-twisted yarn with a stretch elongation of 140%. The obtained false-twisted yarn is used as warp yarn to weave plain fabric. The obtained fabric had excellent stretchability, but the fabric quality was slightly poor. The results are shown in Table 3.

[Comparative example 3]

Except for using nylon 610 (N610) with a relative viscosity of 2.7, a melting point of 225°C, and a moisture content of 200 ppm as the crystalline polyamide (B), a polyamide potential wound composite yarn with a length of 66 dtex 12 filament, an elongation at break of 16.3%, and a wet heat shrinkage stress variation of 200% was obtained using the same method as in Example 5.

The obtained polyamide latent crimp composite fiber yarn was rubbed and false-twisted to obtain a false-twisted yarn with a stretch elongation of 145%. The obtained false twisted yarn Used as warp yarn to weave plain fabrics. The obtained fabric had excellent stretchability, but the fabric quality was poor. The results are shown in Table 3.

[Comparative example 4]

Except for setting the moisture content of the crystalline polyamide (B) to 2000 ppm, a polyamide potential wound composite yarn with a 66 dtex 12 filament, an elongation at break of 21.1%, and a wet-heat shrinkage stress variation of 170% was obtained using the same method as in Example 5.

The obtained polyamide latent crimp composite fiber yarn was rubbed and false-twisted to obtain a false-twisted yarn with a stretch elongation of 175%. The obtained false-twisted yarn is used as warp yarn to weave plain fabric. The obtained fabric had excellent stretchability, but the fabric quality was slightly poor. The results are shown in Table 3.

[Table 3]

As shown in Tables 1-3, Examples 1-10 yield fabrics with excellent tensile strength and superior fabric quality.

Although the invention has been described in detail using specific methods, it will be clear to those skilled in the art that various changes and modifications can be made without departing from the intent and scope of the invention. Furthermore, this application is based on Japanese Patent Application No. 2021-036047, filed on March 8, 2021, and its entire contents are incorporated herein by reference.

10a～10c: Side-by-side composite polyamide fibers 10d: Eccentric core-sheath type composite polyamide fibers 11: Center of eccentric core-sheath type composite polyamide fibers 12: Center of the core (serving as the center of the crystalline polyamide (A) in the core) A: Crystalline polyamide (A) B: Crystalline polyamide (B) L: Distance M: Length

Claims (9)

A polyamide wound yarn comprising a parallel or eccentric core-sheath composite polyamide fiber formed from crystalline polyamide (A) and crystalline polyamide (B), having a wet-heat shrinkage stress variation of 150% or less, wherein the crystalline polyamide (A) is nylon 6, nylon 66, nylon 4, nylon 11, nylon 12, nylon 410, nylon 510, nylon 610, nylon 612, and at least one of the following as main components, wherein 95 mol% or more of the repeating structure is a single amide, aminocarboxylic acid, or a copolymer of diamine and dicarboxylic acid as a combination, and the crystalline polyamide (B) is nylon 610 or nylon 612. The polyamide wound yarn as described in claim 1 is formed by bonding the crystalline polyamide (A) and the crystalline polyamide (B) in a side-by-side or eccentric core-sheath configuration, wherein the crystalline polyamide (A) and the crystalline polyamide (B) are polyamides with different shrinkage properties. The polyamide wound yarn as described in claim 1 or claim 2, wherein the wet heat shrinkage stress is 0.001 cN/dtex to 0.50 cN/dtex. The polyamide wound yarn as described in claim 1 or claim 2, wherein the elongation at break is 15% to 100%. The polyamide wound yarn as described in claim 3, wherein the elongation at break is 15% to 100%. A false-twisted yarn, including the polyamide crimped yarn described in any one of claims 1 to 5. The false-twisted yarn according to claim 6, wherein the hygrothermal shrinkage stress variation rate is 150% or less. The false-twisted yarn according to claim 6, wherein the stretch elongation is 70% to 300%. A fabric including the false-twisted yarn according to claim 8.