JPH02293409A - Production of polyamide fiber - Google Patents

Abstract

PURPOSE:To readily obtain crimped yarn at a low cost without passing the yarn through a mechanical processing method such as false twisting texturing by melt spinning a polyamide, applying a specific amount of an aqueous solution from one side of respective filaments while being kept at a high temperature, quenching the yarn and then taking off the quenched yarn at a high speed. CONSTITUTION:A polyamide, such as nylon 66 or nylon 6, is melt spun and an aqueous solution in an amount of <=20wt.%, preferably <=10wt.% based on the throughput of respective filaments is then applied from one side of the respective filaments to quench the filaments while being kept at >=150 deg.C, preferably 150-210 deg.C temperature. The resultant quenched filaments are subsequently taken off at >=4000m/min speed to afford the objective fiber capable of producing natural crimps.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing polyamide fibers capable of exhibiting natural crimp. More specifically, the present invention relates to a method for producing polyamide fibers that produces natural crimps by a method based on high-speed spinning rather than crimps obtained by mechanical processing such as false twisting.

[Conventional technology]

BACKGROUND ART By mechanical processing methods such as false twisting and pressing, crimped yarns of bolyamide such as nylon 6 and nylon 66 are produced in large quantities and are widely used in socks, carpets, and the like. However, manufacturing crimped yarn by these mechanical processes requires an expensive processing machine and a large amount of energy and manpower.

Therefore, the cost of the obtained crimped yarn is extremely high.

On the other hand, nylon 66 is disclosed in Japanese Patent Application Laid-open No. 57-154409
When spinning at high speeds of 08,000 m/min or higher, an asvilator is used between the spinneret and the winder to impart a birefringent index distribution in the radial direction to the resulting fiber single filaments (yarns). It is disclosed that but,
The nylon 66 fiber obtained by this method has a birefringence distribution in the radial direction, that is, the interference fringes observed with a transmission interference microscope are symmetrical with respect to the central axis of the single fiber, and natural crimp does not occur in principle. It is. Furthermore, this conventional technique does not mention natural crimp at all.

[Problem to be solved by the invention]

The present inventors proposed a method for obtaining a polyamide crimped yarn without going through a complicated machining process in Japanese Patent Application No. 63-140.
No. 504 (unpublished at the time of filing of this application) proposed a method in which water is added to the yarn immediately after spinning to rapidly cool it, and then natural crimp is caused by heat treatment. Furthermore, in order to improve the drawback that the spring constant is small due to the crimped yarn obtained by this method having coiled crimps, Japanese Patent Application No. 63-274611 (unpublished at the time of filing of this application) was proposed. proposed a method of increasing the spring constant of crimped yarn by heat-treating polyamide fibers, which can obtain a relatively high crimp elongation rate under low tension, by heat treatment under no tension.

In this method, a crimped yarn having a high crimp elongation of 50% or more is stretched and heat treated to some extent, so the crimp elongation must be lowered and the spring constant must be increased. For that reason,
In order to obtain a high crimp elongation rate and a high spring constant, the crimp elongation rate obtained by heat treatment under no tension is required to be quite high. In order to obtain a crimped yarn with such a high crimp elongation rate, it is necessary to add water to the yarn at a position where the temperature of the yarn greatly exceeds 200°C, and the range that can be obtained is extremely large. It becomes limited. For this reason, it is necessary to rapidly cool the yarn at a position closer to the spinneret, and operability is extremely reduced. Therefore, it has been quite difficult to easily obtain a crimped yarn with a high crimp elongation rate.

An object of the present invention is to provide a method for easily and inexpensively obtaining a polyamide crimped yarn having an improved spring constant and a high crimp elongation rate.

[Means to solve the problem]

As a result of intensive research on crimped yarn obtained by a method based on high-speed spinning of polyamide, the present inventors found that it is easy to improve the spring constant by adjusting the amount of aqueous liquid applied to the yarn immediately after spinning. The present invention was achieved by discovering that a crimped yarn with a high crimp elongation rate that can be obtained can be obtained.

That is, the above-mentioned object of the present invention is to produce fibers by melt-spinning polyamide, and while each yarn after spinning maintains a temperature of 150°C or higher, 2Qwt% of the discharge amount of each yarn is
Apply the following amount of aqueous liquid from one side of each yarn and rapidly cool it.
This is achieved by a method for producing polyamide #a fiber, which is characterized by drawing at a speed of 1,000 m/min or more.

In the present invention, the molten polyamide is extruded through the holes of a plurality of spinnerets in the same manner as in the conventionally known melt spinning method.
Melt-spun the fibers. At that time, each yarn extruded from the hole of the spinneret is cooled by atmospheric gas, but in the present invention, while each yarn maintains a temperature of 150°C or higher,
It is extremely important to apply 2Qwt% or less of the aqueous liquid to the discharge amount of each yarn from one side of each yarn. As the aqueous liquid, water or an aqueous oil solution used in ordinary spinning is employed. Water may be used for convenience. If the temperature of the yarn at the position where the aqueous liquid is applied is less than 150°C, or if the aqueous liquid is applied from around each yarn, even if the yarn is drawn at a speed of 4000 m/min or more. ,
After that, no natural crimp occurs due to heat treatment. Water liquid is
It must be 2Qwt% or less with respect to the discharge amount of each yarn. If it exceeds 2Qwt%, natural crimp will not be sufficiently produced by heat treatment, and if the amount of aqueous liquid applied changes, unevenness will occur in the crimp between single yarns or in the longitudinal direction of the yarn, resulting in poor socks. This is a major drawback when used as carpet.

The amount of the aqueous liquid applied is preferably 15 wt% or less, more preferably 1Qwt% or less. The preferable temperature of the yarn at the position where the aqueous liquid is applied is 150°C to 210°C,
On the other hand, the temperature of the applied aqueous liquid is preferably 50°C or less. Although various methods can be used to apply the aqueous liquid, it is preferable to use a nozzle guide method or a roll method, and a nozzle guide is particularly preferable because it allows easy control of the amount of aqueous liquid applied to each thread.

The yarn take-up speed must be at least 4000 m/min. If it is less than 4000 m/min, the orientation of molecules and crystals is insufficient, and mechanical properties such as strength are insufficient, making it unsuitable for practical use.

When the manufacturing method of the present invention is applied to a fiber having a substantially circular cross-sectional shape, a fiber with asymmetrical interference fringes as shown in FIG. 1(a) by a transmission interference microscope is obtained.

For comparison, FIG. 1(b) shows the interference fringes of a fiber made by a method other than the present invention, and in this case the interference fringes are symmetrical. These interference fringes indicate the birefringence distribution in the radial direction of the fiber, which means that the thermal properties vary in the radial direction.

The fact that the interference fringes are asymmetric means that this variation in thermal properties is eccentric from the center of the fiber diameter. Due to the fact that this thermal property varies in the radial direction of the fiber and is eccentric from the center of the diameter, the fiber obtained by the manufacturing method of the present invention does not naturally crimp due to subsequent heat treatment. will occur.

According to the production method of the present invention, if the aqueous liquid is applied at the same position and the amount applied is reduced, the birefringence distribution in the radial direction of the fiber does not change, that is, the variation in thermal properties remains the same. The eccentricity from the center of the diameter increases, and a high degree of crimp is achieved.

On the other hand, when the manufacturing method of the present invention is applied when the cross-sectional shape of the fiber is irregular, fluctuations in thermal properties cannot be confirmed by interference fringes, but as in the case of a circular cross-section,
Thermal properties fluctuate and distribute asymmetrically within the fiber cross section, and this is thought to be the cause of spontaneous crimp development due to subsequent heat treatment.

Better crimp occurs when the fibers have an irregular cross section than when the fibers have a circular cross section. This is thought to be because the variation in thermal properties within the cross section is greater in the irregularly shaped cross section.

The polyamide in the present invention includes nylon 66, nylon 6, nylon 4,6, nylon 12, nylon 610, etc. obtained by known polymerization methods. These polyamides may contain various additives.

In order to develop natural crimp, the polyamide fibers obtained according to the present invention can be made into filaments or knitted fabrics and then subjected to wet or dry heat treatment, or by the method shown in Japanese Patent Application No. 63-274611. It is also possible to develop natural crimp with an improved constant and use it as a knitted fabric.

In some cases, the fibers obtained by the production method of the present invention already exhibit natural crimp. Even in such a case, the subsequent heat treatment will further increase the crimp (increase in crimp elongation rate) and make it stronger (increase in crimp elastic modulus).

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to Examples.

The method for measuring the properties of the polyamide fiber of the present invention will be described below.

(a) Yarn temperature The yarn temperature was measured in a non-contact manner along the spinning line using a scanning infrared thermometer.

(Example) Crimping elongation ratio and crimping elastic modulus A small skein of 20 turns of polyamide fiber was made using a measuring machine with a frame circumference of 1.125 m. The obtained small cold was heat-treated with boiling water at 98° C. for 5 minutes under no load, and then left in a room at constant temperature and humidity (temperature 20±2° C., relative humidity 65±2%) all day and night.

A load of 2 mg/d is applied to the humidity-conditioned fibers, and the wind length l is measured after 30 seconds. Next, add 0 to the small skein. A load of 1 g/d is applied, 30 seconds later, the wind length fl2 is measured, and the load is immediately removed. After 2 minutes, apply a load of 2 mg/d to the small skein and
After 0 seconds, the skein length l3 is measured.

The crimp elongation rate and elastic modulus are expressed by the following formula.

In addition, the measurement takes into account the variation of the samples, and the measurement
The O point was measured and the average value is shown.

(c) Observation of interference fringes and eccentricity ratio (x/R) using a transmission interference microscope A transmission quantitative interference microscope manufactured by Karl Zeiss Jena, East Germany was used, and an electric field vector parallel to the fiber axis was used using green light (wavelength 549 mμ). Observe interference fringes with . To determine whether the interference fringe is symmetrical or asymmetrical with respect to the central axis of the fiber, observe the fiber while rotating it in the circumferential direction, and observe the lowest point or the first point of the V-shaped interference fringe as shown in Figure 1(a). A U-shaped structure having a portion where interference fringes are observed, where the highest point of the U-shape is not located on the central axis of the fiber, as shown in FIG.

The eccentricity ratio is determined by finding the point where the lowest point of the V-shape or the highest point of the U-shape of the interference fringe deviates from the central axis of the fiber by the method described above, and then calculates the eccentricity ratio by Find the distance X and the fiber radius R, and let R be the eccentricity ratio.

(2) Strong elongation TENSIL manufactured by Toyo Baldwin [IN IITM
-II-20 type tensile testing machine, the initial length was 20 cm, and the tensile speed was 20 cm/min.

Example 1 η measured by dissolving Ig/100cc in 95% sulfuric acid,
=2.62 nylon 66 was spun using the melt spinning apparatus shown in FIG. Melt spinning was carried out at 300° C. through a spinneret with 4 holes of 5 mm diameter. At this time, the spinning speed was kept constant at 7000 m/min, the single fiber denier of the fiber was kept constant at 14 denier, and room temperature water was applied to each yarn from one side by a water supply nozzle guide. At that time, by changing the height of the water supply nozzle guide, that is, the position of the water supply nozzle guide from the spinneret, the temperature of the yarn at the water application position was varied. Furthermore, when applying water at each position, the amount of water applied is 1
It was changed to 00wt% and 20vt%.

The following margin is Example 2 The spinning speed is 2000. 3000, 4000,
5000. Nylon 66 fibers were produced under the same conditions and method as in Example 1, except that the speed was changed to 6000 m/min and the temperature at the point of water application was 180°C. Note that the amount of water applied was constant at 10 wt%. Table 2 shows the properties of the fibers obtained in this example.

As shown in Table 2, when the spinning speed is 4000 m/min and the spinning speed is 4000 m/min, crimp does not occur even if the amount of water applied is reduced at a position where the tip temperature is 180°C.

Table 2 Table 3 [Effects of the Invention] The polyamide fibers obtained by the present invention can be easily obtained into crimped yarns at low cost without undergoing mechanical processing such as false twisting. Furthermore, a crimped yarn having a crimp elongation rate of 50% or more that improves the spring constant can be obtained very easily,
Crinkling spots between single yarns and in the yarn length direction are also almost eliminated.

Fibers with a circular cross section are used for clothing such as socks.Example 3: Nylon 66 with η = 2.69, which was measured in the same manner as in Example 1, was cut into a Y cross section using a melt spinning machine shown in Figure 2. Melt spinning was carried out at 300° C. through a spinneret with 4 holes. At this time, the single yarn denier was kept constant at 14 denier and the spinning speed was kept constant at 7000 m/min, and the amount of water applied was varied as shown in Table 3. The method of applying water was the same as in Example 1, and water was applied at a position where the temperature of the yarn reached 185°C.

Table 3 shows the characteristics of each fiber. No. of Table 3 No. 6 is substantially cooled by air, and no natural crimp can be obtained by air cooling.

Margin below The surface fibers are suitable for carpeting.

[Brief explanation of drawings]

Figure 1 is an example of fiber interference fringes (indicating the fine shape or structure of fibers) observed with a transmission interference microscope.
FIG. 1(a) shows an example of fibers obtained by the method of the present invention which are asymmetrical with respect to the central axis, and FIG. 1(b) is an example of symmetrical fibers with respect to the central axis of the fibers. FIG. 2 is a schematic diagram of the apparatus used in the embodiment of the invention. 1... Spin head, 2... Spinneret, 3...
...Filament, 4...Aqueous liquid supply nozzle 5
... Winding section. (a) Figure (b) Figure

Claims (1)

[Claims] 1. When producing fibers by melt spinning polyamide,
While each yarn after spinning is maintained at a temperature of 150°C or higher, an aqueous liquid is applied from one side of each yarn in an amount of 20 wt% or less based on the discharge amount of each yarn, and the yarn is rapidly cooled at 4000 m/min. A method for producing polyamide fiber, characterized by taking it off at a speed higher than or equal to the above.