JPH01314718A - Production of polyamide multifilament yarn - Google Patents

Abstract

PURPOSE:To obtain a crimped yarn, capable of producing natural crimps and suitable as socks, stockings or carpets by melt spinning a polyamide, applying an aqueous solution from one side to respective filaments while keeping the respective filaments at a specific temperature or above, quenching the filaments and taking off the resultant quenched filament yarn at a high speed. CONSTITUTION:A polyamide is melt spun and an aqueous solution is applied from one side to respective filaments after the spinning while being kept at >=150 deg.C, preferably 150-210 deg.C. The resultant filaments are then quenched and taken off at >=4000m/min speed to afford the objective multifilament yarn. Furthermore, nylon 66, nylon 6, nylon 4.6, nylon 12, nylon 610, etc., are cited as the polyamide.

Description

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

C. Prior Art] Crimped yarns of polyamides such as nylon 6 and nylon 66 are produced in large quantities by mechanical processing methods such as false twisting and pressing, 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 8,000 m/min or higher, birefringence distribution is imparted to the resulting multifilament single yarn in the radial direction by spinning via an aspirator between the spinneret and the winder. is disclosed. However, the nylon 66 multifilament 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 filament, and natural crimp is in principle It does not occur. Also,
This conventional technique does not mention natural crimp at all.

[Problem to be solved by the invention]

The present invention has the same performance as mechanically processed polyamide crimped yarn, so it can be used for applications such as socks and carpets, and can be manufactured at a lower cost than these processed yarns. An object of the present invention is to provide a method for producing a polyamide multifilament that can exhibit natural crimp.

[Means to solve the problem]

As a result of intensive research on high-speed spinning of polyamide, the present inventors have obtained a multifilament that can generate natural crimp through subsequent heat treatment by applying an aqueous liquid to the filament immediately after spinning and rapidly cooling it. The present invention was achieved based on the discovery that

That is, the above-mentioned object of the present invention is to melt-spun polyamide to produce multifilaments, in which each filament after spinning, that is, each single filament, has 150
This is achieved by a method for producing a polyamide multifilament characterized by applying an aqueous liquid to each filament from one side while maintaining the temperature above .degree. C., rapidly cooling the filament, and then taking it off at a speed of 4000 m/min or above.

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 multifilament. At this time, each filament extruded from the spinneret hole is cooled by atmospheric gas, but in the present invention, while each filament maintains a temperature of 150°C or more, an aqueous liquid is poured from one side of each filament. Give. 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 filament I at the position where the aqueous liquid is applied is below 150°C, or if the aqueous liquid is applied from the surroundings to each filament 1, even if the drawing speed is 4000 m/min or more, Even if it is pulled at high speed, natural crimp occurs due to subsequent heat treatment. The preferred temperature of the filament 1- at the position to which the aqueous liquid is applied is 150°C to 210°C, and the temperature of the aqueous liquid to which the force is applied 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.

The multifilament drawing 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 filament having a substantially circular cross-sectional shape, a filament with asymmetrical interference fringes as shown in FIG. 1(a) by a transmission interference microscope is obtained. For comparison, FIG. 1(b) shows interference fringes of a filament 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 filament, 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 diameter of the filament.

Due to the fact that this thermal property varies in the radial direction of the filament and is eccentric from the center of the diameter, the filament obtained by the manufacturing method of the present invention is Natural crimp will occur.

On the other hand, when the manufacturing method of the present invention is applied to cases where the cross-sectional shape of the filament is irregular, it is not possible to confirm fluctuations in thermal properties due to interference fringes. Thermal properties fluctuate and distribute asymmetrically within the core, and this is considered to be the cause of spontaneous crimp development due to subsequent heat treatment. Better crimp occurs when the filaments have an irregular cross section than when the filaments 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.

In the present invention, crimp development means that the crimp elongation rate is 10% or more,
Polyamide in the present invention refers to nylon 6 obtained by a known polymerization method.
6, nylon 6, nylon 4,6, nylon 12, nylon 610, etc. These polyamides may contain various additives.

In order to cause the polyamide multifilament obtained by the present invention to develop natural crimp, it may be subjected to a wet or dry heat treatment after being made into a filament state or a knitted fabric. The temperature of the heat treatment is preferably 80°C or higher. In some cases, the fibers obtained by the production method of the present invention already exhibit natural crimp. Even in this case, the crimp will further increase (increase in crimp elongation rate) by subsequent heat treatment,
It also becomes stronger (increased crimp modulus).

〔Example〕

The present invention will be explained in detail with reference to Examples.

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

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

(b) Crystal orientation degree The degree of crystal orientation of polyamide multifilament can be measured using an X-ray generator (RU-200PL) manufactured by Rigaku Corporation, a fiber sample measuring device (FS-3), and a goniometer (SG-9).
, a scintillation counter is used in the counter, a liquid height analyzer is used in the counting section, and the cu is made monochromatic with a nickel filter.
Measured as Ka=vA (λ-1,5418 people). The X-ray generator operates at 30 kV and 80 mA.

The goniometer is set to the 2θ value of the diffraction peak obtained from the equatorial diffraction curve. Using the symmetrical transmission method, the azimuthal direction is scanned from -30° to +30° and the diffraction intensity in the azimuthal direction is recorded. Furthermore, the diffraction intensity in the azimuth directions of −180° and +180° is recorded.

At this time, scanning speed is 4°/min, chart speed is 1
0m1/min, time constant 1 second, collimator 2
Dragon φ, receiving slit length 1.91, width 3.5
It is 111.

To determine the degree of crystal orientation from the obtained diffraction intensity curve in the azimuthal direction, the average value of the diffraction intensities obtained at +180° is taken, and a horizontal line is drawn to use it as a base line. Draw a perpendicular line from the top of the peak to the baseline and find the midpoint of its height. A horizontal line passing through the midpoint is drawn, the distance between the intersection of this horizontal line and the diffraction intensity curve is measured, and this value is converted into an angle (°), which is defined as the orientation angle H. The degree of crystal orientation is given by the following formula.

(c) Crimping elongation rate and crimp elastic modulus A small skein of 20 turns of polyamide multifilament was made using a measuring machine with a frame circumference of 1.125 m.

The obtained small skein was heat-treated with boiling water at 98°C for 5 minutes under no load, and then left in a room at constant temperature (temperature 20±2°C, relative humidity 65±2%) day and night.

A load of 2/d is applied to the moisture-conditioned fibers, and the skein length 11 is measured after 1 minute. Next, apply a load of 0.1 g/d to the small skein, measure the skein length I12 after 1 minute, immediately remove the load, apply a further load of 2 g/d to the small skein, and after 1 minute, measure the skein length I12.
Measure 3. The crimp elongation rate and crimp elasticity are expressed by the following equations.

In addition, in consideration of sample variations, measurements were performed using one sample per sample.
Measurements were made at 0 points and the average value is shown.

(d) Observation of interference fringes using a transmission interference microscope Using a transmission quantitative interference microscope manufactured by Karl Zeiss Jena, East Germany, interference fringes having an electric field vector parallel to the fiber axis are observed using green light (wavelength 549 mμ). To determine whether the interference fringes are symmetrical or asymmetrical with respect to the central axis of the fiber, observe the fiber while rotating it in the circumferential direction, and find the lowest point or U of the 7-shaped interference fringe as shown in Figure 1 (a). A character shape having a portion where the highest point is not on the central axis of the fiber and where interference fringes are observed is determined to be asymmetric.

(B) Strong elongation TENSILON UTM-n manufactured by Toyo Baldwin Co., Ltd.
Measurement was performed using a -20 type tensile tester at an initial length of 20 cm and a tensile speed of 20 cmZ.

-1~3, '1.2 η measured by dissolving 1 g/100cc in 95% sulfuric acid
.

-2,62 nylon 66 was melt-spun at 300° C. using the melt-spinning apparatus shown in FIG. 2 through a spinneret having four holes of 0.3 diameter. At this time, the spinning temperature was kept constant at 7000 m for 7 minutes, the single yarn denier of the multifilament was kept constant at 14 denier, and room temperature water was applied to each single yarn from one side by a water supply roll. At that time, by changing the height of the water supply roll, that is, the position of the water supply roll from the spinneret, the temperature of the single fiber at the water application position was varied.

Table 1 shows the symmetry and degree of crystal orientation of the interference fringes of the single yarn before heat treatment, and the crimp elongation rate and crimp elasticity after heat treatment.

Comparative Example 1 in Table 1 is essentially air-cooled, and the interference fringes are symmetrical with air cooling, indicating that no natural crimp occurs.

As shown in Examples 1 to 3, the filament was heated to 150°C.
Excellent crimp can be obtained by cooling while maintaining the temperature above.

Table 1: Position where water was applied - Distance from the spinneret surface Timber Single yarn temperature at the position where wood was applied Examples 4 to 6, Comparative Examples 3 and 4 ηr-2 measured in the same manner as Examples 1 to 3 , 55 nylon 66 was melt-spun at 300° C. using the melt-spinning machine shown in FIG. 2 through a spinneret having four holes with a Y-shaped cross section. At this time, the spinning speed was kept constant at 7000 m for 7 minutes, the denier of the single multifilament yarn was 14 denier, and water was applied to each single yarn from one side by a water supply roll. At that time, the height of the water supply roll, that is, the single yarn temperature at the water application position was varied.

Table 2 shows the degree of crystal orientation of the multifilament before heat treatment, the crimp elongation rate, crimp elastic modulus, strength and elongation after heat treatment.

As shown in Table 2, sufficient crimp cannot be obtained when water is not applied or when water is applied at a single yarn temperature of less than 150°C.

Table 2 in the margin below: "Position where water was applied - Distance from the spinneret surface Single yarn temperature application at the position where water was applied 117-9, 615
,6 Spinning speed 2000, 3000, 4000, 50
A multifilament of nylon 66 was produced under the same conditions and method as in Examples 4 to 6 except that the temperature at the point where water was applied was changed to 180° C. and 6000 m 2 /min.

Table 3 shows the degree of crystal orientation before heat treatment, the crimp elongation rate, crimp elastic modulus, strength and elongation after heat treatment.

As shown in Table 3, when the spinning speed is less than 4000 m/min, even if water is applied at a position where the single yarn temperature is 180°C,
No crimp occurs.

Below is Table 3 in the margin [Effects of the Invention] The polyamide multifilament obtained by the present invention provides a crimped yarn having the same performance as a crimped yarn obtained by a mechanical processing method such as false twisting. Therefore, crimped yarns for socks and carpets can be obtained at a much lower cost than those obtained through mechanical processing.

Multifilaments with circular cross sections are suitable for use in clothing such as socks, and multifilaments with irregular cross sections are suitable for use in carpets.

[Brief explanation of the drawing]

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

Claims (1)

[Claims] 1. When manufacturing multifilaments by melt-spinning polyamide, while each filament after spinning maintains a temperature of 150°C or higher, an aqueous liquid is applied to each filament from one side to rapidly cool it, and the speed is 4000 m/min or higher. A method for producing polyamide multifilament, characterized in that the polyamide multifilament is drawn at a speed of .